It's about time we added an AUTHORS file (cloudtools#432)

* It's about time we added an AUTHORS file

Thanks everyone :)

* Fix some style

* Use Garrison's real name

AUTHORS.rst

@@ -0,0 +1,50 @@
+Authors
+=======
+
+Stacker was designed and developed by the OpsEng team at `Remind, Inc.`_
+
+Current Maintainers
+-------------------
+
+- `Michael Barrett`_
+- `Eric Holmes`_
+- `Ignacio Nin`_
+- `Russell Ballestrini`_
+
+Alumni
+------
+
+- `Michael Hahn`_
+- `Tom Taubkin`_
+
+Thanks
+------
+
+Stacker wouldn't be where it is today without the open source community that
+has formed around it. Thank you to everyone who has contributed, and special
+thanks to the following folks who have contributed great features and bug
+requests, as well as given guidance in stacker's development:
+
+- `Adam McElwee`_
+- `Daniel Miranda`_
+- `Troy Ready`_
+- `Garison Draper`_
+- `Mariusz`_
+- `Tolga Tarhan`_
+
+.. _`Remind, Inc.`: https://www.remind.com/
+
+.. _`Michael Barrett`: https://github.com/phobologic
+.. _`Eric Holmes`: https://github.com/ejholmes
+.. _`Ignacio Nin`: https://github.com/Lowercases
+.. _`Russell Ballestrini`: https://github.com/russellballestrini
+
+.. _`Michael Hahn`: https://github.com/mhahn
+.. _`Tom Taubkin`: https://github.com/ttaub
+
+.. _`Adam McElwee`: https://github.com/acmcelwee
+.. _`Daniel Miranda`: https://github.com/danielkza
+.. _`Troy Ready`: https://github.com/troyready
+.. _`Garison Draper`: https://github.com/GarisonLotus
+.. _`Mariusz`: https://github.com/discobean
+.. _`Tolga Tarhan`: https://github.com/ttarhan