Clear models
Merge branch 'services-cost-graph' into feature/clean-models
Clean models
fix tests
Merge branch 'services' into feature/clean-models

Conflicts:
	src/ralph_scrooge/models/service.py
	src/ralph_scrooge/models/usage.py
fix
Merge branch 'services' into feature/clean-models

Conflicts:
	src/ralph_scrooge/tests/utils/factory.py
fix notics
create new migration
f -> t

f -> t
Merge pull request #273 from kula1922/feature/clean-models

Feature/clean models