Orientation

This PR:

- uses tablet style when the screen height is too small
- displays optional buttons (time, rotate, offline) correctly with a small scren height
- moves all map buttons in a single button group element 
- centralize the positioning of buttons in app.less
- Fix #1794 

Test [here](http://mf-geoadmin3.dev.bgdi.ch/dev_orientation/)

Nice one :)