* Use the repository as context, instead of released .tar.gz
* Remove version information from Dockerfile, and let Docker Cloud handle it
* Add .dockerignore
Next steps:
1. Connect repository in Docker Cloud
2. Setup automated builds:
- A push on `master` branch triggers build for `unstable` tag
- A tag matching /^v[0-9]+(\.[0-9]+){2}$/ triggers build for a same-named tag
Refer to #1914
Sah