Ignore nova limits set to '-1'

In case nova server has quotas turned off, e.g. when it uses
NoopQuotaDriver, nova-api returns '-1' for corresponding resources which
obviously means 'INFINITY'. In this case we should not check resource
template for any limits and should pass resource creation as-is.

Change-Id: Idaf485719e384f3a613031c7ff272d55798e6e77
Closes-Bug: #1310710
Co-Authored-By: Dmitry Borodaenko <dborodaenko@mirantis.com>
Merge "Ignore nova limits set to '-1'" into stable/icehouse