JERSEY-2602: WADL classes in jersey-server are generated incorrectly

 - fix - not generating wadl classes during build
 - added test

Updated Maven Checkstyle plugin to 2.12.1 (2.11 -> 2.12.1)

 - suppressed checkstyle for WADL classes

Change-Id: I32faf861673b84c7766a048d43216b9e8477daf5
Signed-off-by: Michal Gajdos <michal.gajdos@oracle.com>