Add argument "register"

[julkue]

After running bower register xxx xxx I get the following error: [InvalidArgumentException] Command "register" is not defined.

This is a important functionality because bower does not have all packages from github!

[mefiblogger]

:+1:

[devthejo]

+1

[garak]

Feel free to open a PR

[julkue]

@garak I've already switched to the original one as of missing arguments