Tool for finding pin names/modes

A script from
http://captainunlikely.com/blog/2013/09/26/managing-the-gpio-pins-on-a-beaglebone-black/bbpins.pl
that is useful for finding pin names/modes. It doesn't run because I
don't have the right Perl modules installed, but a string in the body
has some useful information.

I probably should rewrite this in Python.
Adjusting interrupts entry

After reading the documentation for the gpio interrupt driver I'm using,
I think that this is the appropriate way to speficy the interrupt for
the ENC.