JERSEY-2596: Servlet 3 deployment doesn't work in some cases.

 - using ResourceConfig created in JerseyServletContainerInitializer (in apps with servlet-class defined)
   to initialize ServletContainer in WebConfig (default 2.5 way)
 - integration test
 - lowered log messages in JerseyServletContainerInitializer

Change-Id: I9223a5b3f30c886785c30aa53b3ee8314fb0affc
Signed-off-by: Michal Gajdos <michal.gajdos@oracle.com>
Merge "JERSEY-2596: Servlet 3 deployment doesn't work in some cases."