Add basic SecurityGroup model

This adds a basic SecurityGroup model and query methods.

Related to blueprint unified-object-model

Change-Id: I92a18529add3e46e801a30e35cdbd4932c890a55
Add Instance.security_groups

This makes Instance load the security_groups list when it
is present in the database object.

It also refactors the way info_cache is saved, so that it
can more easily apply to security_groups as well.

Related to blueprint unified-object-model
Fixes bug 1192003

Change-Id: Ifb028e17ffef7c14557e6389a650d66ce8e9b25c
Make InstanceList filter non-column extra attributes

This is a no-op right now, but we need to avoid passing things
like fault to the instance_get_all() queries. This will be used
in changes to follow.

Related to blueprint unified-object-model

Change-Id: I66355a024b139fa6c579e04885ba52f9697381fe
Refresh volume connections when starting instances

This patches adds network and block device information to the signature
of the power_on method on the virtualization driver. The relevant call
sites are also modified to provide the required information. The libvirt
implementation of power_on has been altered to re-establish network and
volume related connections.

Fixes bug: 1188326

Change-Id: If617b570e082e3aa321414a2680a3aa0754f6153
Merge "Refresh volume connections when starting instances"
Merge "Add basic SecurityGroup model"
Merge "Add Instance.security_groups"
Merge "Make InstanceList filter non-column extra attributes"
Merge remote-tracking branch 'm_src_repo/citrix-fixes' into build-temp