Fix schema-to-template for empty schema

if schema is {}, the
schema_to_parameters_and_properties(schema)
function shouldn't get an error, and return
{}, {} for parameters and properties

Closes-Bug: #1341985

Change-Id: Ic206ba64811bf43080a9deebb7c3b4c19134c43d
Fix updating from an empty stack

Change-Id: Ic63e1998316b27a431e856fe43b9ad8cc9dd887a
Closes-bug: #1343171
Use six.add_metaclass instead of __metaclass__

According to http://docs.openstack.org/developer/hacking/ it should
be preferred to use six.add_metaclass instead of __metaclass__.

Change-Id: I1775035ea998b78a52c28ffe71dda2ede1377b31
Don't resolve attributes before create

Change-Id: Idf0120b8c7fb46300462720136002bc7d7d68d31
Closes-Bug: #1332317
Merge "Fix schema-to-template for empty schema"
Merge "Fix updating from an empty stack"
Merge "Use six.add_metaclass instead of __metaclass__"
Merge "Don't resolve attributes before create"