Add adcdl script to download files from ADC.

Originally found it on the internet long time ago and modified a few
times to fit my needs.

Needs $HOME/.adc/.credentials to have your ADC login/password seperated
by a new line.
Add scan and $ command. Update OS X stuff.
Merge branch 'master' of github.com:Neal/dotfiles

* 'master' of github.com:Neal/dotfiles:
  Add killrsub function to kill broken open rsub connections.