Refactor exception handling in the OSPF protocol

- removed unnecessary throws of Exception from methods
- converted throws of generic Exception to specific OspfParseException

Change-Id: I9d07167d92f221a234e9eba4c6082deb165afc0b
diff --git a/protocols/ospf/api/src/main/java/org/onosproject/ospf/controller/OspfMessage.java b/protocols/ospf/api/src/main/java/org/onosproject/ospf/controller/OspfMessage.java
index 9949146..460457f 100644
--- a/protocols/ospf/api/src/main/java/org/onosproject/ospf/controller/OspfMessage.java
+++ b/protocols/ospf/api/src/main/java/org/onosproject/ospf/controller/OspfMessage.java
@@ -17,6 +17,7 @@
 
 import org.jboss.netty.buffer.ChannelBuffer;
 import org.onlab.packet.Ip4Address;
+import org.onosproject.ospf.exceptions.OspfParseException;
 
 /**
  * Representation of an OSPF message.
@@ -48,9 +49,9 @@
      * Reads from ChannelBuffer and initializes the type of LSA.
      *
      * @param channelBuffer channel buffer instance
-     * @throws Exception might throws exception while parsing buffer
+     * @throws OspfParseException might throws exception while parsing buffer
      */
-    void readFrom(ChannelBuffer channelBuffer) throws Exception;
+    void readFrom(ChannelBuffer channelBuffer) throws OspfParseException;
 
     /**
      * Returns OSPFMessage as byte array.