Return world_readable and guest_can_join in /publicRooms

Allow guest users to join and message rooms

Get display name from identity server, not client

Don't fiddle with results returned by event sources

Overwriting hashes returned by other methods is poor form.

Fixes: SYN-516

... merely because I was trying to figure out how it worked, and couldn't.

SYN-513: Include updates for rooms that have had all their tags deleted

Conflicts:
	synapse/storage/tags.py

Remove accidentally added ID column

Implement pagination, order by and groups in search

Fix tox config after fa1cf5ef

Retry dead servers a lot less often

Squash-merge of PR #345 from daniel/anonymousevents

Remove fields that are both unspecified and unused from the filter checks

This follows the same flows-based flow as regular registration, but as
the only implemented flow has no requirements, it auto-succeeds. In the
future, other flows (e.g. captcha) may be required, so clients should
treat this like the regular registration flow choices.

Remove unused arguments and code

Conflicts:
	synapse/notifier.py

Remove the LockManager class because it wasn't being used