Till now, when switching between different views, we were switching
different bindings on repo controller. This was quite innefficient,
because then we needed to add bindings also from other controllers and
it's hard to manage such structure when we would like to add specialized
controllers (like LogController).
The new setup is more declarative, meaning that we do such things on the
router and set things on proper controllers. The only drawback is that
now we need to setup a few observers instead of bindings for "current"
views (ie. when viewing the newest repo or when viewing the last build
in current repo).
At this point it may not look like huge improvement, but it will open a
way to more refactorings.
