Adding support for GCE v1 and Cloud SDK

Compute Engine is now Generally Available and with that comes a new version of 'gcutil' that is now bundled with Cloud SDK.  This PR contains support for:

* Cloud SDK's bundled version of 'gcutil'
* New variables for specifying your puppet_master FQDN and if the puppet agent should be automatically started
* Live instance migration is on by default but can be disabled with `on_host_maintenance => false`
* GCE v1 fixes for persistent disk and images with embedded kernels