Vx.x.x (Pre-release)

Changes since v2.2:

Add CONTRIBUTING guide
Add Issue and Pull Request templates
Add Dockerfile
Fix fsnotify import
Update README to reflect new repository ownership
Update CI scripts to separate linting and testing
- Now using gometalinter for linting
Move Go import path from github.com/bitly/oauth2_proxy to github.com/pusher/oauth2_proxy
Repository forked on 27/11/18
- README updated to include note that this repository is forked
- CHANGLOG created to track changes to repository from original fork