[#144] 'install git-hook' command.
Merge branch 'master' into jfacorro.144.install.git-hook
[#144] [#143] Added new command to help info.
[#144] Added new command to help info.
Merge branch 'jfacorro.144.install.git-hook' of https://github.com/inaka/elvis into jfacorro.144.install.git-hook
Merge pull request #146 from inaka/jfacorro.144.install.git-hook

[Closes #144] 'install git-hook' command