Add "rat" and "findbugs" targets. Copied from Ant's check.xml buildfile and slightly modified for Ivy.
Add "rat" and "findbugs" targets. Copied from Ant's check.xml buildfile and slightly modified for Ivy.

git-svn-id: bddd0b838a5b7898c5897d85c562f956f46262e5@961246 13f79535-47bb-0310-9956-ffa450edef68

pantsbuild/ivy,pantsbuild/ivy