WFLY-858 - re-enable PojoEndpointAuthenticationTestCase

"Socked Closed" issue (introduced in JDK 6u38) was fixed in JDK 7u40. WF is supported on JDK 7+.
We can re-enable tests which were failing intermittently because of it.

Details on https://issues.jboss.org/browse/WFLY-858