Refactor UI code

[inkel]

This seems like a scary big PR, but what it does is actually simplify a lot of the code.

1. all of the different views were moved into models of their own, so we can have better management of what happens where.
2. several unnecessary custom Tea messages were removed.
3. code for "handling" errors was added, and by handled I mean it will be displayed in red.
4. a confirmation step was added before removing disks.

I suggest reviewing on a per commit basis first to get an idea of the changes, and then finally an overall look.