Resolves #2: support for checkstyle to be run via maven

Because the latest maven checkstyle plugin uses checkstyle 5.7, I manually added a checkstyle 6.2 check.  When checkstyle supports java 8 fully in checkstyle 6.2+ then we can undo this.
Where did you find the original source for this file? If we can't include it as a maven dependency, I'd at least like it to have a link to the original.