Login Controller

This PR had only Login controller and views for him.
![login](https://cloud.githubusercontent.com/assets/9048513/4976940/bf1e8d04-68fb-11e4-8145-cea6eb02e150.jpg)
![registration](https://cloud.githubusercontent.com/assets/9048513/4976942/c04c79de-68fb-11e4-8020-fe2917d961c7.jpg)

put constraints initialization process in separate method