webadmin: Auto update quota by template

In the VM popup - when a template is selected, update the quota to the
quota of the selected template.

Change-Id: Ia1d70b895738218e551128c73415a1cbd33e8915
Bug-Url: https://bugzilla.redhat.com/924928
Signed-off-by: Ofri Masad <omasad@redhat.com>