Bash: clean up prompt color code
Bash: disable set term title in $PS1
Launch tmux on login

This will create or connect to an existing tmux session named after the
username when the user logs in to Bash with an interactive session.

Further, when the user logs into Bash via a tmux panel, we show the MOTD
and last login time (same as is displayed when logging into a machine
via SSH.)
Tmux: fix bug where text was underlined/bold
Tmux: bind  to detach, logout of ssh
Bash: add 'lastlogin' command

Prints a prettier version of 'lastlog', same as pam_lastlog.so module does.