The case of the missing swf

1. Added a check to ensure `dist/build/uploader/assets/flashuploader.swf` exists during a release build.  If it is not found, you will get the following error during the `release-validate` task:

        Fatal error: Failed to find: release/3.10.1pre/dist/build/uploader/assets/flashuploader.swf

2. Added GRUNT_SKIP_TESTS, which you can set in your environment to skip unit testing.  Similar to [GRUNT_SKIP_BUILD](https://github.com/yui/grunt-yui-contrib/blob/master/tasks/build.js#L8). Very helpful while debugging.  The diff might appear big, but it's just an if/else wrapper around the original contents, which were unchanged.

3. Extraneous whitespace cleanup, thanks to my editor.