Improved GitHub integration

Happy Friday y'all. We have some great news before you sign off for the weekend: The GitHub Integration has received an update, with some features you have been waiting for! As of today, GitHub integration can synchronize in both directions, from Sleekpan to Github and vice versa, on private an public repos!
## All features in a nutshell:
- Status updates > Sleekplan to GitHub and vise versa
- Create Sleekplan posts from GitHub issues
- Push posts from Sleekplan to GitHub
- Auto-close discussion for linked posts
To work correctly you may need to re-install the integration! Don't worry, already linked posts won’t get lost!
[feedback: 9457]