Add templates for selected resource extensions.
Add templates for selected resource extensions.

Related to bug 852141; adds XML serialization and deserialization for
the following extensions:

* FlavorExtraSpecs (os-flavor-extra-specs)
* Floating_ips (os-floating-ips)
* Hosts (os-hosts)
* Keypairs (os-keypairs)
* Quotas (os-quota-sets)

Change-Id: I96ace8252f8f77612ab8c866e03eff8faee2c12b

n0ano/ganttclient