Added Gitter badge

Closed #48

Author: gitter-badger

README.rst

@@ -19,6 +19,10 @@
 .. image:: https://img.shields.io/badge/license-MIT-blue.svg
     :alt: MIT License
 
+.. image:: https://badges.gitter.im/Join%20Chat.svg
+   :alt: Join the chat at https://gitter.im/codingjoe/django-stdimage
+   :target: https://gitter.im/codingjoe/django-stdimage?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge
+
 Django Standarized Image Field
 ==============================