Change CMD to NAME
Clena up Makefile
git subrepo clone git@github.com:ingydotnet/git-hub-travis plugin/git-hub-travis

{"local":
  {"subdir":  "plugin/git-hub-travis"
  ,"action":  "clone"}
,"remote":
  {"url":     "git@github.com:ingydotnet/git-hub-travis"
  ,"branch":  "master"
  ,"commit":  "e7b5788"}
,"git-subrepo":
  {"version": "0.1.0"
  ,"commit":  "57b9507"
  ,"origin":  "git@github.com:ingydotnet/git-subrepo"}}
Support git-hub plugins!

`carloslima/git-hub-plugin` is an existing plugin. Added it to a
./plugin/ directory as a subrepo, and made git-hub search under
./plugin/*/lib/ for commands.

This means people can clone new repos under the plugin directory and
they will be installed.