Add a Gitter chat badge to README.md
secusu/secusu now has a Chat Room on Gitter
@a-komarev has just created a chat room. You can visit it here: https://gitter.im/secusu/secusu.
This pull-request adds this badge to your README.md:
If my aim is a little off, please let me know.
Happy chatting.
PS: Click here if you would prefer not to receive automatic pull-requests from Gitter in future.