Add support for using lxc as a vagrant provider via vagrant plugin

To use, run 'vagrant plugin install vagrant-lxc' to install the plugin
Use 'vagrant up --provider=lxc' to create the vagrant instance
When using an lxc vagrant provider, the hostname may not be localhost
Merge pull request #314 from maurizi/topic/lxc-vagrant-provider

Add support for using lxc as a vagrant provider