Adding Intent Impl and shell command to install simple intent
diff --git a/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentInstallationException.java b/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentInstallationException.java
new file mode 100644
index 0000000..3b17cf1
--- /dev/null
+++ b/core/net/src/main/java/org/onlab/onos/net/intent/impl/IntentInstallationException.java
@@ -0,0 +1,22 @@
+package org.onlab.onos.net.intent.impl;
+
+import org.onlab.onos.net.intent.IntentException;
+
+/**
+ * An exception thrown when intent installation fails.
+ */
+public class IntentInstallationException extends IntentException {
+    private static final long serialVersionUID = 3720268258616014168L;
+
+    public IntentInstallationException() {
+        super();
+    }
+
+    public IntentInstallationException(String message) {
+        super(message);
+    }
+
+    public IntentInstallationException(String message, Throwable cause) {
+        super(message, cause);
+    }
+}