Update maven-compiler-plugin to 3.2.

This update brings a bunch of stability enhancements as described at
http://jira.codehaus.org/secure/ReleaseNote.jspa?projectId=11130&version=19091.

Change-Id: I278b02e0b9ae5193e1a86370e08ad389c962d6a0
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>