Begin porting to ubuntu
Finish porting to Ubuntu
Clarify ubuntu prerequisites
Add the silver searcher (back) to Ubuntu

There was an old PPA that hasn't been maintained, so I thought that was
not the best idea.
https://launchpad.net/~tomaz-muraus/+archive/the-silver-searcher

There are a few .deb packages made, but they weren't available for
32-bit systems or over SSL.
http://swiftsignal.com/packages/

I couldn't find a good source for an Ubuntu package, so I'm compiling
from source on the master branch of the main github repository.
Change URLs to main thoughtbot repo before merge
Remove chmod zsh hack, switch to aptitude
Update README, restructure to articulate broader linux support than just ubuntu
Abort under unsupported distros. Better messaging.
Install shell
Check lsb_release in a more portable fashion
Update and upgrade packages before doing anything
Refactor package installation to work across supported platforms