Remove disabled navigation in ISIS

#### Small UX improvement in ISIS template

##### What is it?
On ISIS when we are editing something (basically when we are in singular view) the main navigation becomes greyed out but cpanel and user menu are still visible. This PR hide them. 

#### Tests
Apply the patch and move around in the admin area

##### In pictures:
Normal view
![screenshot 2014-10-16 13 34 35](https://cloud.githubusercontent.com/assets/3889375/4661252/56b0838c-5521-11e4-8ec0-545311a61367.png)

Enter editing mode
![Uploading Screenshot 2014-10-16 16.59.22.png . . .]()