bin: Script to list available system colors

Taken from http://tldp.org/HOWTO/Bash-Prompt-HOWTO/x329.html.
Startup: Improvements to .bashrc, .vimrc, .tmux.conf

* Explicitly call a "hidden" script for sensitive information
* Allow tmux to work nicely on RHEL virt machines
* Use a nicely colored welcome prompt
* Explicitly set up the vim backspace behavior for system compatibility

Testing: Manual.