Oj.is.nullOrUndefined

Small change to `OJ.is` namespace to add missing `OJ.is.nullOrUndefined` function used by `dom.coffee`, and accompanying test.  See: `is.coffee` and `test.is.coffee`.  Also fixed what I think was a precedence error in `OJ.is.nullOrEmpty` - coffee was generating a pretty broken condition.

Release build along for the ride.

As an aside - it appears gulp was not compiling tests.  I added this but then noticed that an old `gulp-coffee` dep is pinned with older version of coffee (1.7.0 vs 1.7.1) so I just manually recompiled.  I wasn't sure if there was a reason, but if you'd like I can go ahead and update that dep and gulpfile to compile coffee files.