Update deps for therubyracer and libv8 to resolve build issues on FreeBSD. Resolves Iussue#3446 .
Merge pull request #3457 from jrmithdobbs/fix-freebsd-bundle-install

Update deps for therubyracer and libv8 resolve build issues on FreeBSD...
Improve header and wording.
Section for important notes.
Fix therubyracer dependencies
Merge branch 'notes-in-installation-guide' of /home/git/repositories/gitlab/gitlabhq
Merge branch 'header-in-contributing-guide' of /home/git/repositories/gitlab/gitlabhq
Use existing methods for branch names: Ex use @repository.branch_names instead of @repository.heads.map(&:name)
Move Commit and Repository logic to lib/gitlab/git
specs for Gitlab::Git::Repository and Gitlab::Git::Commit
Remove grit logic from app/
Fix tests and remove app/models/repository.rb
Decorate Gitlab::Git::Commit with Commit
Remove Commit & Tree decorators
Add Repository model to proxy request to Gitlab::Git::Repositoty and decorate commits with Commit model
rake task to clear redis cache
remove Tree/Commit decorator usage from controllers
Move some decorator logic to helpers
Remove decorator calls and methods from views. Repalace with helper calls when needed
Extend models functionality with old decorator methods. Use Repository model