(feat) Implemented Middleware for Persistent.
(feat) Publicized data field.
(test) Tested Persistent.
(feat) Refactored to use RWLock instead of Mutex.
(test) Updated tests to use RWLock.
(doc) Added hitcounter example.
(fix) Fixed travis.
(feat) Refactored to use RWLock instead of Mutex.
(feat) Scaffolded Share middleware.
(feat) Impled Clone for Shared.
(feat) Switched to using ShareableMiddleware.
(feat) Added public constructor.
(feat) Added convenience mixin for Chain.