JERSEY-2517: Create mechanism to automatically register features/providers
   even when autodiscoverable and metainf/services mechanisms are disabled

 - introduced internal SPI ForcedAutoDiscoverable
 - BV, WADL, JSON-P, Monitoring migrated to ForcedAutoDiscoverable
 - added new test + updated older ones
 - note in migration guide

Change-Id: I120f0e695980e90e86085f34b23608d9a3876027
Signed-off-by: Michal Gajdos <michal.gajdos@oracle.com>