Add Ruby code to determine full path to supporting files referenced
in all Vagrantfiles. This will allow more effective use of Vagrant
commands when not in the same directory as the Vagrantfile.
* move etcd.overrides to /etc/default/etcd ( more linuxy, upstart script tries to source that already ).
* template etcd.defaults using values from servers.yml
* provision installs curl if doesn't exist ( I use vbox and my base image doesn't have it )
* provision is now roughly idempotent
* provision starts etcd or restarts it if already running
* gitignore to not save template written .default files
