Adds themes/secrettriangle.zsh-theme

Features:
* Blue bar takes width of terminal, helpful to find where commands were entered when scrolling through thousands of lines of output (uses `TRAPWINCH` to automatically resize when terminal is resized)
* Actual `$PROMPT` is 2 characters long, so long command lines don't get truncated as quickly
* Nonzero return codes highlighted in red
* Path truncated if too long
* Supports `git` and `virtualenv`
* Red `#` instead of green `%` when using theme as root

![Screenshot](http://i.imgur.com/NUx5Q0B.png)