Remove GitHooks::PreCommit.validate
Add rubocop validator
Add GitHooks::Git

It is a wrapper to git ruby gem.
Add Git#added_or_modified
Rewrite GitHooks:PreCommit::Rubocop
Add GitHooks::Git#current_branch
Rewrite GitHooks::PreCommit::PreventMaster
Add GitHooks::RspecExecutor
Add GitHooks::Git#clean?
Rewrite GitHooks::PreCommit::Rspec