Fix bug that forced closed any instance of the terminal

My shell-fu was not sufficient for the task at hand. I was abusing many
assumptions inside .bashrc, .profile and .bash_profile by using the exit
0 command inappropriately.

I've changed the .profile and .bash_profile to source the .bashrc file,
and I moved the machine specific settings out of .profile and into
.bashrc.local so as to no longer step on the toes of my systems.