Add David Crowder to Author list.

Thank you for your continued contributions @david-crowder! You should now have admin privileges on this repository and should be able to merge this pull request (and future requests), and perform triage tasks, etc., etc.

Have a big red button good sir. Use it wisely:
![day-of-the-doctor-tv-trailer-32](https://cloud.githubusercontent.com/assets/413832/5559348/2102b626-8d0f-11e4-8635-9bff0dd90b3d.jpg)