Remove unnecessary using self.properties.get for more
clear code. Using properties.get(prop, default) causes
next issues:
1. properties.get(prop) if prop not in properties_schema
will return None instead of expected KeyError.
2. properties.get(prop, default) returns "default" value
if current properties is not presented in properties_schema.
So using self.properties.get() makes sense only when we plan
to use this property with default option in another resource,
which has not it in property schema.
This patch replaces this methods in resources/openstack folder.
Change-Id: I523eb3feacb0cb7a16a928a92896ce56188e376f
4b5f296acc