Allow parallel installation of gems

http://robots.thoughtbot.com/post/59584648154/parallel-gem-installing-using-bundler
Stage all deleted files with one command

http://dan.brubakerhorst.com/blog/stage-all-deleted-files-in-a-git-repository/
Enabling "one commit per pull request"

http://ndlib.github.io/practices/one-commit-per-pull-request/