Customised bash-it to my liking.

This commit is my initial toying around with bash-it. It contains a myriad of
small fixes for exists bash-it files as well as a collection of my own plugins
and custom stuff.
Modified my theme to use bash-it colors.

This required some fiddling. Had to change the __make_ansi function inside
themes/colors.theme.bash to make it work. For some reason it wasn't interpreting
the backslash escaped square brackets properly. Not sure why.
Tweaked my prompt theme.
OSX changes.
Stopped setterm outputting if it existed.
Various upgrades to my personal config.
Merge branch 'sam-arch-linux' of https://github.com/samwho/bash-it into sam-arch-linux
Various OSX and bundler based changes.