first whack at rvm support in vagrant-cachier
adding requires for the rvm files
loading in the rvmdir classes in the plugin file.

This should now work...
minor changelog updates.
renaming rvmdir -> rvm_path
adding rvm installation to the vagrant file
adding rvm info to the docs
Merge pull request #21 from cromulus/rvm_support

Rvm support
Minor tweak to the readme
Install RVM for vagrant user and prevent installation if already installed
v0.2.0