Adding try/catch for errors thrown when YUIDoc dislikes options

Added a simple `try/catch` where Grunt options are parsed for the `yuidoc` task.  With bad options (easy mistake for a new user of the package), the task fails without much feedback.  The `try/catch` hands off the error to stdout via Grunt's fail/warn handler.

Sets a Grunt [exit code](http://gruntjs.com/exit-codes) of `1`, "Fatal error".