Moved BGP code and Router code into their own bundle.

The main goal of this is to allow routing code to be used by multiple
applications.

Changes include:
 * Created an onos-app-routing bundle and moved BGP code and routing code
   into it.
 * Created an onos-app-routing-api bundle as a common API bundle between
   onos-app-routing and onos-app-sdnip, to prevent circular dependencies.
 * Moved API classes into onos-app-routing-api bundle.
 * Made Router and BgpSessionManager into OSGi components. This is not quite
   clean, because there is still a chain of start() method calls from SdnIp
   through to BgpSessionManager to preserve startup order. This should be
   revisted so components can be started using activate()
 * Created BgpService and RoutingService APIs to glue different components
   together.
 * Many unit test changes. A lot of the previous unit tests spanned the
   Router and IntentSynchronizer classes, but this is not possible any more
   since these classes are in different bundles. I had to rewrite some of
   these tests so that each unit test class only tests one real class. A
   nice side-effect is that the tests are now simpler because each test
   tests less functionality.
 * Removed SdnIp test seeing as it doesn't run automatically, was already
   broken and has been largely superseded by other unit tests and the nightly
   functional tests.

Change-Id: I70ecf5391aa353e99e7cdcf7ed38a530c87571bb
diff --git a/apps/routing/src/main/java/org/onosproject/routing/bgp/BgpKeepalive.java b/apps/routing/src/main/java/org/onosproject/routing/bgp/BgpKeepalive.java
new file mode 100644
index 0000000..186dfeda
--- /dev/null
+++ b/apps/routing/src/main/java/org/onosproject/routing/bgp/BgpKeepalive.java
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2014 Open Networking Laboratory
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.onosproject.routing.bgp;
+
+import org.jboss.netty.buffer.ChannelBuffer;
+import org.jboss.netty.buffer.ChannelBuffers;
+import org.jboss.netty.channel.ChannelHandlerContext;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * A class for handling BGP KEEPALIVE messages.
+ */
+final class BgpKeepalive {
+    private static final Logger log =
+        LoggerFactory.getLogger(BgpKeepalive.class);
+
+    /**
+     * Default constructor.
+     * <p>
+     * The constructor is private to prevent creating an instance of
+     * this utility class.
+     */
+    private BgpKeepalive() {
+    }
+
+    /**
+     * Processes BGP KEEPALIVE message.
+     *
+     * @param bgpSession the BGP Session to use
+     * @param ctx the Channel Handler Context
+     * @param message the message to process
+     */
+    static void processBgpKeepalive(BgpSession bgpSession,
+                                    ChannelHandlerContext ctx,
+                                    ChannelBuffer message) {
+        if (message.readableBytes() + BgpConstants.BGP_HEADER_LENGTH !=
+            BgpConstants.BGP_KEEPALIVE_EXPECTED_LENGTH) {
+            log.debug("BGP RX KEEPALIVE Error from {}: " +
+                      "Invalid total message length {}. Expected {}",
+                      bgpSession.remoteInfo().address(),
+                      message.readableBytes() + BgpConstants.BGP_HEADER_LENGTH,
+                      BgpConstants.BGP_KEEPALIVE_EXPECTED_LENGTH);
+            //
+            // ERROR: Bad Message Length
+            //
+            // Send NOTIFICATION and close the connection
+            ChannelBuffer txMessage =
+                BgpNotification.prepareBgpNotificationBadMessageLength(
+                message.readableBytes() + BgpConstants.BGP_HEADER_LENGTH);
+            ctx.getChannel().write(txMessage);
+            bgpSession.closeSession(ctx);
+            return;
+        }
+
+        //
+        // Parse the KEEPALIVE message: nothing to do
+        //
+        log.trace("BGP RX KEEPALIVE message from {}",
+                  bgpSession.remoteInfo().address());
+
+        // Start the Session Timeout timer
+        bgpSession.restartSessionTimeoutTimer(ctx);
+    }
+
+    /**
+     * Prepares BGP KEEPALIVE message.
+     *
+     * @return the message to transmit (BGP header included)
+     */
+    static ChannelBuffer prepareBgpKeepalive() {
+        ChannelBuffer message =
+            ChannelBuffers.buffer(BgpConstants.BGP_MESSAGE_MAX_LENGTH);
+
+        //
+        // Prepare the KEEPALIVE message payload: nothing to do
+        //
+        return BgpMessage.prepareBgpMessage(BgpConstants.BGP_TYPE_KEEPALIVE,
+                                            message);
+    }
+}