core: Introducing findbugs filter to bll module

Introducing findbugs to bll module.
In order to generate findbugs report use
"mvn site" and look for findbugs.xml at the target/site
directory (this may take several minutes)

Marking as WIP as obviously this should be implemented to
other modules.
I would like you to review and share your opinions

Thanks

Change-Id: I26b9cafc1832022693a7386277972a7e48a53f0d
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>