Cleanup prompt script.

Tone down colors used by the prompt script by switching out bright
colors for more subtle colors, and by changing the green color used by
the directory path to a light cyan color.

Make the terminal multiplexer information optional with new
PROMPT_ENABLE_SCREEN_INFORMATION environmental variable.

Add support for displaying terminal multiplexer information for TMUX.
Cleanup bashrc configuration files.

Move PATH and environmental variable setup to login configuration
script. By moving PATH setup steps to the login configuration script,
rather than the interactive configuration script, we prevent the PATH
from being appended to itself in each successive invocation of a Bash
shell.

Add additional variable sanitation by wrapping all variables in quotes.

Fix watch function by inverting the check for the inotifywatch command.