Fix findbugs RCN_REDUNDANT_NULLCHECK_OF_NONNULL_VALUE in AgentManagerImpl.java Assert isn't used in runtime, null is properly checked in method

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>

This closes #444

engine/orchestration/src/com/cloud/agent/manager/AgentManagerImpl.java

@@ -457,7 +457,6 @@ public class AgentManagerImpl extends ManagerBase implements AgentManager, Handl
     }
 
     protected AgentAttache getAttache(final Long hostId) throws AgentUnavailableException {
-        assert (hostId != null) : "Who didn't check their id value?";
         if (hostId == null) {
             return null;
         }