This rework isn't entirely complete here, I haven't
checked the tests yet and I didn't really test anything
furthermore yet, so bear with this commit breaking things.

Besides that, the goal of this commit was to rework the
filterSrv singleton into a factory, so we move the filterSrv
instance around via the scope. This should be a better solution
than the current situation, because services shouldn't contain
model data - the scope should.
This will eventually straighten out control flow between dashboard,
filters and so on, and allow us to leverage angularJS mechanics more.
The latter has already started, since I could rework a bit of the
existing event infrastructure to watches on times.