Add skeleton of CacheAdapter
Add StorageBackend 'interface'
Add dict backed storage backend
Update readme with the rationale behind the package
Add mock to tox deps
Add an optional backing dict for DictStorageBackend
DictStorageBackend.get returns None when the key is missing
Add Cache class
Add the validation and cacheability filters concept
Add skeleton of RFC 2616 filters
Add skeleton of httpbis filters
Add filter usage to adapter