VMware: enable driver to work with postgres database

The hypervisor version is expected to be an integer and not
a string.  The nova/utils.py change is part of the following
patch but is not being backported as it adds new feature
functionality and is therefore not acceptable for backport

https://review.openstack.org/#/c/36073/

Closes-Bug: #1195139
(cherry picked from commit e2efa57ab2fb03b92f80abbf612a257c28475140)

Conflicts:

	nova/tests/virt/vmwareapi/test_vmwareapi.py
	nova/virt/vmwareapi/host.py

Change-Id: Ifac9ca3480191413e3a02f0dae94e452707ae82f
Merge "VMware: enable driver to work with postgres database" into stable/havana