Updated maven-pmd-plugin to set targetJdk to 1.7 to avoid annoying compile-time warnings.  See RE-1650
Moving pose-parent's default opower.checkstyle.checks properties up to opower-parent because archmage uses those defaults too.  See NAN-239
Merge pull request #12 from tvaughan77/master

Centralizing some common properties and updating PMD plugin to know about our targetJDK