RBAC / [WFLY-490] / [WFLY-455] Adding support for loading group membership information from LDAP

This pull request includes a number of commits adding support for loading group information from LDAP and related tasks: -
  [WFLY-567] Improvements to service name generation and dependency injection.
  [WFLY-2007] Adding unit tests to test security realms directly, currently testing involves deploying a web app configured with a domain that calls a realm!
  [WFLY-455] The adding of support for loading groups from LDAP, including a community contribution from Flemming Harms which has been adapted further.
  [WFLY-2082] Re-use the LDAP connection used for authentication during the group loading step.
  [WFLY-2084] Where the distinguished name of the user was discovered during authentication allow for it's re-use during group loading.