Code cleanup: Replace old hashes and remove trailing spaces

Fix check git version.

maintenance policy

Add minitest to Gemfile. Fix #3826

Checking is "yes" only if git version equals "1.7.10" exactly.

There are occasions where minitest is not bundled in packaged
versions of ruby that some OSes distribute (eg Fedora). Adding
minitest to Gemfile ensures that it gets loaded and tests can run.
Signed-off-by: Axilleas Pipinellis <axilleas@archlinux.gr>

fix API route to delete project hook

Fixed forgotten unicorn to puma in a comment.

link contribution guide to test section in README

Create DeployKey & DeployKeysProject models. Bulding many to many relation between deploy keys and projects

Changed forgotten unicorn to puma in the init script

Remove 2000 char limit on issue description