feat: Add support for Cinder LVM backend

[wilkers-steve]

Is this a bug report or feature request? (choose one): feature request

Kubernetes Version (output of kubectl version):

Helm Client and Tiller Versions (output of helm version):

Development or Deployment Environment?: Both

Release Tag or Master:

Expected Behavior:

What Actually Happened:

How to Reproduce the Issue (as minimally as possible):

Any Additional Comments:

After discussing desired functionality from Cinder in development mode in #258, we concluded that LVM support would be ideal. Adding LVM support makes sense from a development point of view because it's functional and allows us to create volumes and attach them to VMs as opposed to leveraging Ceph, but LVM's also a backend that's used in production. Adding support for LVM really tackles two issues, and I think it's a good step forward in the effort to remove development mode flags in our charts. Documentation for using LVM in a local instance (laptops ideally) will accompany the work towards solving this issue.