Swapped out coloured output to use rainbow. Fixes #7.

This patches some weird terminal colour issues that popped up on Ubuntu
linux and more specifically, zsh.
Added in add-domain and delete-domain commands. Fixes #6.
Updated readme to add new methods
Bump version to 1.2.0
Merge pull request #8 from jacobbednarz/add-better-terminal-colour-support

Add better terminal colour support and add new domain commands