Need to implement image_id for openstack

[mstine]

inception deploy blows up now for openstack b/c of:

https://github.com/cloudfoundry-community/inception-server/blob/master/lib/inception/providers/clients/openstack_provider_client.rb#L48

Snag appropriate logic from here:

https://github.com/cloudfoundry-community/bosh-bootstrap/blob/v0.10/lib/bosh-bootstrap/cli.rb#L1032-L1051

[drnic]

Temporary workaround is to look up the ID for a desired image, place it directly into settings.yml and re-run inception deploy:

inception:
  image_id: db6cc9ba-ac2f-483b-8d95-c1a61b431fcc
  initial_user: root

[drnic]

Simplest UI is to prompt for the flavor ID string

[drnic]

Note: also need to prompt for initial user (ubuntu or root etc)

[drnic]

Clones #16