Overhaul view and sort behavior

Big changes to view, sort, routing, filtering, etc, etc, etc...

Todo
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- [x] stream search -- race between $scope.updater and stream controller, need to send the filter
- [x] page search -- simple matter of fixing the ugly ng-show conditions at the bottom of the viewer template perhaps with more verbose, obvious variables, or scope/controller functions to abstract the route details from the template a bit
- [x] Check on https://github.com/hypothesis/h/pull/1436#discussion_r16705832 (leave as is 2014-08-29)
- [x] Restore "no results for “query”" message.
- [x] Annotations don't watch for changes
- [x] forced login -- a comment about ideas for that [here](https://github.com/hypothesis/h/issues/1020#issuecomment-53400218)

The `group:__world__` string is now littered across the codebase. Would be nice to make it a constant, and here use an explicit method such as `vm.canReadWorld()` or similar.