Merge branch '828-update-briar-logo-in-app' into 'master'

Update all logos

The launcher icons are now in mipmap folders which is the recommended practice, because on a low-res device, the high res drawables are stripped from the app. This is bad when the user decides to show the app icons really big on the launcher and the high-res drawables are not available anymore.

The old launcher icon seemed to have some sort of 3D effect.
![device-2016-12-13-134037](/uploads/84db532df3821ad74ba57719f0763b7b/device-2016-12-13-134037.png)

Navigation Drawer Old:
![device-2016-12-13-124112](/uploads/465b817d2e0bbbd50b461ea32686c933/device-2016-12-13-124112.png)
Navigation Drawer New:
![device-2016-12-13-132428](/uploads/3c3530bfc515525dd8f66abfa52d1142/device-2016-12-13-132428.png)

Closes #828

See merge request !459