[bug 849480] Simplify get_next_url.

- Improve test coverage of sumo.utils.get_next_url.
- Simplify implementation, since we no longer need to implement
  is_safe_url ourselves.
- Drop untested semantics/checks, like LOGIN_URL.
- Early returns are nice and clean.
Fix from review comment.

Silly code, you can be simpler!
[bug 856233] Fix index call

We updated to a new elasticutils which has differen bulk_index args.

Plus bulk_index doesn't chunk the indexing, so I dropped the chunk
size to 100 which is a better chunk size for bulk indexing.
[Bug 823891] Recent revision list with filtering.

This can be filtered by user, locale, and by date. It uses a fragment
loader to change the filtered data and to change pages without reloading.