remove map._label variable, doesn't seem to be used by anything.
Don't force reflow when removing a label and don't do setOpacity things as they don't do anything as we are already removed. Greatly increases performance of hideLabel
Make jake lint work.

Add a package.json so you can "npm install" all the dev dependencies.
Merge pull request #34 from danzel/master

Improve .hideLabel() performance and some misc cleanups