Fixed potential class-loader memory leak.

The perf. improvement changes related to JERSEY-2002 and delivered as part of 1334e891a2edf91ad7407348435de8d70ce99695 commit introduced potential class-loader memory leaks. This commit fixes the leak by removing any static references to class (and classloader) instances.


Change-Id: Ibf18afa350af33e3e0e9e8485141a1030c58b045
Signed-off-by: Marek Potociar <marek.potociar@oracle.com>