Manual cherry-pick of 4f73f440

This allows us to set the shell for the nova users and provide a ssh
public and private key.

https://github.com/stackforge/puppet-nova/commit/4f73f440a60142255f7fb3ab97a74dc14b5f51fa
Merge pull request #1 from matthewfischer/stable/havana

support for managing ssh keys

This allows us to set the shell for the nova users and provide a ssh
public and private key.

Manual cherry-pick of stackforge@4f73f440