Add git-overwritten to ~/bin

https://github.com/mislav/dotfiles/blob/master/bin/git-overwritten
Removing awesome_print from irbrc: it's broken

C'mon awesome_print.

Breaks IPAddr: https://github.com/michaeldv/awesome_print/issues/134

Breaks the Money gem: https://github.com/michaeldv/awesome_print/issues/139

Fixes both: https://github.com/michaeldv/awesome_print/commit/f36e788584801aa528a284693b54faeee4467a6d

But over five months from that fix there's still no new version in
RubyGems. I'm out!