Fix #1669 on develop

Add links to forks/watchers/stars in new layout header

Docker Container: Init 1 & Initialisation

- Now using a setup script before starting the app. The separation of
the run script and the setup script will make service initialisation a
little bit clearer
- Now calling start.sh script as ENTRYPOINT and S6 as CMD. This way
when running the container with just a shell script, the start.sh
script will be launched before, making debugging easier
- Added note about `.dockerignore` ignored during Docker Hub Automated
Build

Several bugfixes in Docker build

- Removed unnecessary variables
- Fixed symbolic links creation
- Fixed enter point
- Less intermediate containers

New approach to Gogs Docker Container

- VOLUME for ‘/data’
- Usage of S6 as PID 1 Process
- Usage of ‘socat’ so linked container (like databases) are binded to
localhost
- OpenSSH, Socat Link and Gogs are supervised using S6
- Size of container reduced to ~75Mo

Implemented #1721: see users who forked/starred/watched a repository

Set USER env variable so installation can complete successfully.

Fix admin repos new ui

Fix admin organization new ui

New admin notice UI based on user list example

Fix `go get` not working when there is a username or repository name with some uppercase letters.