Make Neutron resources reference standard attr table

Make Neutron resources reference standard attr table

This adds a new 'standardattributes' table and adds a foreign-key
references from ports, subnets, networks, subnetpools, routers,
securitygroups, and floatingips to this table.

This will make it easy to add new things to the schema like
timestamp fields or anything else that applies to multiple types
of Neutron resources. The new fields would just be added to the
'neutronresources' table instead of being duplicated across each
resource's table. Or, if the the relationship is 1-to-many (e.g. tags),
the new association table would be related to the 'standardattribute'
table.

Related-Bug: #1496802
Change-Id: Iaa3ba81a7e9cae09cea153720b29879d8cc9a080