Delete code we don't need right now

Squashed commit of the following:

commit e2044cda2a6b6331f6a05773bf4326071cca1046
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Dec 10 19:36:02 2014 +0100

    Should be it

commit ea240e586e4d494a84c3c8e4dc661c650bcc3d54
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Dec 10 19:33:02 2014 +0100

    Even more ...

commit d08371c13cf3bce735a4e98e64b6e530e04a216b
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Dec 10 18:39:16 2014 +0100

    More cleaning

commit 5253f88d6a3171a1a01f059e8f846ed588a2ec6c
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Dec 10 18:36:49 2014 +0100

    More cleaning ...

commit ce63a969ad62e42dda4608c85a78192a9882c762
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Dec 10 14:18:57 2014 +0100

    ... clean ....

commit b5619f9a03e233fad05f1df5a2bdd8eb595de302
Author: Thomas Schank <DrTom@schank.ch>
Date:   Wed Dec 10 13:17:53 2014 +0100

    Cleaning ...
delete old permission tables
latest & favorite media entries & collections in dashboard
Revert "latest & favorite media entries & collections in dashboard"

This reverts commit a19207e349b3e04fd6d517e22f2b2c70b3e665b0.
Cleanup and reorganize `/doc`: database oriented stuff
rubocop & linted source
migrate favorite filter sets too
Link to tests and coverage results from README
Update database schema / entities diagram
...