Closes #21, #13, #12

Add `main` to package.json.

Change store service to a provider

* makes karma-src.coverage.conf.js unnecessary

add method setStore() to set the storage with the storeProvider

```js
angular.module('app', ['angular-storage'])
    .config(function (storeProvider) {
        storeProvider.setStore('sessionStorage');
    })
    .controller('ctrl', function(store) {
        store.set('name', 'wayne');
    });
```

- possible values are 'localStorage', 'sessionStorage' and 'cookieStorage'
- default store is 'localStorage'
- fallback store is 'cookieStorage' when localStorage or sessionStorage are not available in the browser

Add tests (and fix) cookie fallback mode

Fixes #16

Fixes #15

fix(InternalStore): invalid value on parse

if you get an invalid value JSON.parse throws an error

localcache = {
'yolo': undefined // should be "{swag: true, isAuthenticated: true}"
};

store.get('yolo') // JSON.parse error is thrown

localcache

Update bower.json

any version of angular resolve with 1.3

Fixed missing injector inject

Update README.md