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

fork failing when calling initialize_dup

initialize_dup has been made private as of ruby 2.0.0. I have
corrected it to call the publicly available dup method

fix ace editor Syntax Highlighter mode load 404

add proper code/command formatting where missing in CONTRIBUTING.md

link to RSpec. related to #3810

link to spinach in the README. Closes #3810

Internally public projects

updated fork feature to use gitlab-shell for v5 of gitlab

fix http push 401 and 500 with some git clients

See https://github.com/gitlabhq/gitlabhq/pull/3597#discussion-diff-4014638

When asking to fork a project and a project with the same name
already exists (likely from a previous fork), the recovery from
the fork failure would inadvertantly delete the repo of the
existing destination project.

In the public area, project names are shown as static text for
non-logged in users, while logged-in users are given project
names as links they can follow to the project's page.

Assignees are now sorted alphabetically.

[BUGFIX] User suggest at team_members/new not working with relative_url_root