[WIP] Factor blob and blame [failure unrelated]

Created by: cirosantilli

Philosophy: blame is just a type of view for a blob. There is even a toggle button to go between both.

This PR factors:

• the filename holder on blame and blob views
• controller logic for blame which is identical for blame by moving blame into the blob controller

It makes the following UI modifications which increases uniformity between blobs and blames:

• show the branch / path breadcrumb and last commit to the top of the blame
• remove the "blame view" title, since this is already obvious from the view itself, and from the "normal view" toggle button. Same rationale why the show view does not have a "Show view" title.

New:

Old:

We now have more functionality and uniformity with less lines of code.

TODO: the only implementation detail I'm not satisfied with is the route. Can anyone propose a shorter, DRYer way of writing it, possibly as a member of the :blob resource?