ISPN-3398 Unmarshall problem in compatibility mode

https://issues.jboss.org/browse/ISPN-3398

Problem: when the cache receives the operation from a client, it unmarshalls the key/values. However, when the command is replicated, it tries again to unmarshall the key/values, originating the exception.

Solution: the unmarshall only happens if the command's context is local. 

Other fix: the RemoveCommand was comparing the values (conditional remove) without the Equivalence.