fix(Vagrantfile): use amd64-usr for vmware
Merge pull request #54 from philips/usr-image-vmware

fix(Vagrantfile): use amd64-usr for vmware
refactor(plugin): Use cloud-config to provision networks and hostname
refactor(user-data): Fix naming of user-data

The user-data injected by the plugin goes to
/var/lib/coreos-vagrant/user-data.

The user-data provided by the user ends up at
/var/lib/coreos-vagrant/vagrantfile-user-data.
refactor(user-data): Stop touching /etc/environment