Rework the overall interface

[rafaellehmkuhl]

We've been discussing over the last few weeks about a big rework in the interface. The main goal is to make all the screens, menus, bars get consistent with the same design guide.

@ArturoManzoli has made some mockups and the team is discussing around those.

This is a big issue, that aims for a wow-factor on the first user impression, and so will be part of the first stable release.

[rafaellehmkuhl]

Includes the work on #617 and #846.

[rafaellehmkuhl]

@ArturoManzoli I think we can consider this one done, right?