TODO

- add tests
- add insert entity to table storage operations
- add update entity to table storage operations
- add peek messages to queue operations
- add clear messages to queue operations
- add get container properties to blob operations
- add get container metadata to blob properties
- add set container metadata to blob operations
- add get container ACL to blob operations
- add set container ACL to blob operations
- add get blob properties to blob operations
- add set blob properties to blob operations
- add get blob metadata to blob operations
- add set blob metadata to blob operations
- add lease blob to blob operations
- add snapshot blob to blob operations
- add copy blob to blob operations
- add put block to blob operations
- add put block list to blob operations
- add get block list to blob operations
- add put page to blob operations
- add get page regions to blob operations
- general refactoring (particularly of utils.py)
- unify handling of errors (storage ops should throw a wrapped HTTPError where
  appropriate)