Add a Gitter chat badge to README.md

[gitter-badger]

AbsoluteZero2A03/Socksify now has a Chat Room on Gitter

@AbsoluteZero2A03 has just created a chat room. You can visit it here: https://gitter.im/AbsoluteZero2A03/Socksify.

This pull-request adds this badge to your README.md:

Happy chatting.

PS: Click here if you would prefer not to receive automatic pull-requests from Gitter in future.