Notifications

Image of notifications are attached. Different errors messages are displayed depending on what the model methods return.

![error](https://cloud.githubusercontent.com/assets/1191334/4913648/1816cf06-64b6-11e4-91ee-fa961fc79409.PNG)
![success](https://cloud.githubusercontent.com/assets/1191334/4913649/1817b9e8-64b6-11e4-8a3c-f7a84d1f875f.PNG)