Throw exceptions on plugins not being found
Merge branch 'master' of https://github.com/imduffy15/GSoC-2014

* 'master' of https://github.com/imduffy15/GSoC-2014:
  Remove cloudstack submodule
  commit out my cache stuff
  Add caching
  remove cloudstack
  README: fix code indents, add section on common problems
  README: update documentation, add info on Vagrant