[SPARK-1398] Removed findbugs jsr305 dependency

Should be a painless upgrade, and does offer some significant advantages should we want to leverage FindBugs more during the 1.0 lifecycle. http://findbugs.sourceforge.net/findbugs2.html

Author: Mark Hamstra <markhamstra@gmail.com>

Closes #307 from markhamstra/findbugs and squashes the following commits:

99f2d09 [Mark Hamstra] Removed unnecessary findbugs jsr305 dependency