Ensure glance-manage commands are run as correct user/group

Whilst testing stackforge cookbooks w/ ctracey's
cookbook-openstack-omnibus cookbook, I noticed that
/var/log/glance/glance-api.log was getting created as root and this
prevented glance-api from starting as it could not write to the log.

This is a non-issue when using packages as on Ubuntu (at least)
glance-manage db_sync is executed as part of glance-registry's
post-install script as user glance which ensures log file is created
with appropriate ownership.

Change-Id: I56d3e8caa68a32e34baa628a87c5e41b49602c59
Closes-Bug: #1317493
Get the vCenter password from databag for glance


1. Add new attribute openstack_vmware_secret_name to indicate the
databag secret key
2. Get the password from databag if dev mode is false
3. Update the test cases

Implements: blueprint vmware-password-databag

Change-Id: I72f538a16d77cba9c1be9f32e0b37d1ee68e3bbc
Merge "Get the vCenter password from databag for glance"