Feature/minimap hide

hide/show minimap from the toolbar

![minimap-on](https://cloud.githubusercontent.com/assets/2736813/3654861/f2bbd6c6-1171-11e4-90c8-e3a7d1d24a3f.png)
![minimap-off](https://cloud.githubusercontent.com/assets/2736813/3654862/f2bef3f6-1171-11e4-93dc-56ed8a434a70.png)