Add immutable-entity cache container entry for the Hibernate second level cache

Add immutable-entity to https://github.com/wildfly/wildfly/blob/master/clustering/infinispan/extension/src/main/resources/subsystem-templates/infinispan.xml#L39

<cache-container name="hibernate" default-cache="local-query" module="org.hibernate.infinispan">
<local-cache name="entity">
<transaction mode="NON_XA"/>
<eviction strategy="LRU" max-entries="10000"/>
<expiration max-idle="100000"/>
</local-cache>
<local-cache name="immutable-entity">
<transaction mode="NON_XA"/>
<eviction strategy="LRU" max-entries="10000"/>
<expiration max-idle="100000"/>
</local-cache>
<local-cache name="local-query">
<eviction strategy="LRU" max-entries="10000"/>
<expiration max-idle="100000"/>
</local-cache>
<local-cache name="timestamps"/>
</cache-container>

Also see discussion on http://lists.jboss.org/pipermail/hibernate-dev/2015-August/013297.html