DRYs up subnets code

Cleans up some of the create_subnets code through use of helper methods,
and modifies the tests slightly based on the change in database model
creation.
Merge pull request #81 from Cerberus98/cleanup_merge

DRYs up subnets code
Merge remote-tracking branch 'jkoelker/master'

Conflicts:
	quark/plugin.py
	quark/tests/test_quark_plugin.py