rename translations to filters
remove unneeded return statements
extract Resource object
extract set_status method
rename MaybeTimedelta to Timedelta
whitespace
clean up branch coverage report in actor
move activate method to actor
move release method to actor
move revoke method to actor
move update_ttl method to actor
remove unused get_session method
use locked_claim for consistency
Merge pull request #28 from mark-burnett/refactoring

Refactor some functionality out of models.py