GEOS-6080: added standard RoleSource support (Header, RoleService, UserGroupService) to J2EEAuthenticationFilter
GEOS-6080: added more docs to MigrationHelper
Merge pull request #366 from mbarto/geos6080_j2eefilter_roleservice_2

GEOS-6080: added standard RoleSource support (Header, RoleService, UserGroupService) to J2EEAuthenticationFilter