Updating onos-package to display error when karaf-assembly fails.

Also, temporarily adding snapshot repo to karaf-assembly and filed bug to remove it.

Change-Id: I63bf472b3a918beec46e1b1002a29dfcb6cb7253
diff --git a/providers/snmp/pom.xml b/providers/snmp/pom.xml
index 83cd8b9..b25c993 100644
--- a/providers/snmp/pom.xml
+++ b/providers/snmp/pom.xml
@@ -70,7 +70,7 @@
     </dependencies>
     <repositories>
         <repository>
-            <!-- TODO move over to release snmp-core when it becomes available.-->
+            <!-- TODO move over to release snmp-core when it becomes available. ONOS-3646 -->
             <id>oss.sonatype.org-snapshot</id>
             <url>http://oss.sonatype.org/content/repositories/snapshots</url>
             <snapshots>