compute: manage force_raw_images parameter

In Nova, force_raw_images allows to force backing images to raw
format.
Some use-cases require to disable this feature.

Let's use nova::compute class to manage this option, and let at True
by default as this the case in Nova (Juno release).

Change-Id: I4d700204bfd1d297667303b11e572f24dc9af2fc
Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>
Update stdlib dependency to 4.x

puppetlabs/stdlib 4.x is backwards compatible with 3.x and still tested
on Puppet 2.7. Updating stdlib to 4.x allows modules to use newer
functions without breaking older functionality.

Change-Id: Ia3db3ebf69b98631e775be3fa10442f028bbe2ec
Fix wrong rabbit_virtual_host in nova::cells

The wrong rabbit virtual_host is configured in nova::cells.

It should be $::nova::init::rabbit_virtual_host.

Change-Id: Id9af89baed8378586b9c8737cf96faad6d014231
Closes-bug: #1373017
Merge "compute: manage force_raw_images parameter"
Merge "Fix wrong rabbit_virtual_host in nova::cells"