Simplify gitignore
Add vendorize script

* Add vendorize script from gitsh/rcm
  https://github.com/thoughtbot/gitsh/blob/master/vendor/vendorize
* Add `gems:vendorize` and `gems:clean` rake tasks for vendorizing gem
  dependencies.
* Remove old vendorizing rake tasks
Add distribution executable

* Actual executable has proper paths set up for requiring vendorized
  dependencies, and catches all exceptions
* Remove LOADPATH craziness from lib/liftoff