Add info about this package on bower

Thank you for your great library. I think that this lib has the best api among similar modules. Moreover, this service can can store not only strings, but also any object, because it serializes data into JSON.

So I decided to publish this project into bower under the name `localStorageService`. It works good, but worth to add info about it into readme. And another I had to update required version of angular to avoid warnings of incompatible version, when installing this module with lastest stable version of angular.