add Principal to subject

Principal is only added to subject if we use RemotingConnectionCredential or when there is no Principal at all.
If we have valid principal we forget about it.

This causes org.jboss.security.auth.spi.RoleMappingLoginModule to be broken.
I'm not sure if this fix is correct (we can always get Principal from callbackHandler in LoginModule).

Another question what to do with roles? (JbossCallbackHandler don't contain this information) and what to do with roles added in LoginModule
Revert "Merge commit 'refs/pull/5460/head' of github.com:wildfly/wildfly"

This reverts commit eab955383f9f0647f00e5782998de88600ec62a1, reversing
changes made to 3259a05a2ef9601f3515c5a1cc89f1a9cbd419a3.
Merge pull request #5570 from wojtask9/patch-1

add Principal to subject
Merge pull request #5577 from jamezp/WFLY-2616

[WFLY-2616] Add SEVERE logging level to the valid list of levels.
[WFLY-2614] Reserving additional message IDs in the range 21000-21099.
[WFLY-2614] Added error messages to indicate where an invalid alias is specified or if a key store with no keys is provided.
[WFLY-490] domain tests are passing JVM arguments to servers just like integration tests
WFLY-2621 Zero Timeout Stateful EJB Leak (clustered)
Applies WFLY-2590 fix to distributed cache.
Also removes redundant volatile boolean from WFLY-2590 fix.
Fix transient failures in CommandDispatcherTestCase.
[WFLY-2415] Make legacy xml use statistics=true, which is the actual legacy behaviour
[WFLY-2399] make PureTestCase test pass both on web and full profile
Add "memory" artifact to Lucene module.
[WFLY-671] Eliminate huge impact on overall test count; optimize execution speed
WFLY-2059 regression fixed, allow Hibernate envers hibernate.listeners.envers.autoRegister == false
Fix regression in web profile TCK, which doesn't use EJB remoting.
Fix minor typo.
[WFLY-2599] Moved the implicit logging API module dependency adds to the logging subsystem. Added an attribute to enable/disable the dependencies from being added to the deployment.