SH CAS auth via homeserver

Merge pull request #380 from matrix-org/daniel/jenkins-sytest

Run sytests on jenkins

Output results files on jenkins

Outputs:
 * results.xml
 * coverage.xml
 * violations.flake8.log

Pull out jenkins script into a checked in script

Don't complain if /make_join response lacks 'prev_state' list (SYN-517)

Allow guests to /room/:room_id/{join,leave}

Implementation of SPEC-254: roll back the state dictionary to how it looked at
the start of the timeline.

Merged PR https://github.com/matrix-org/synapse/pull/373

Be a bit more careful about how we calculate the state to be returned by
/sync. In a few places, it was possible for /sync to return slightly later
state than that represented by the next_batch token and the timeline. In
particular, the following cases were susceptible:

* On a full state sync, for an active room
* During a per-room incremental sync with a timeline gap
* When the user has just joined a room. (Refactor check_joined_room to make it
  less magical)

Also, use store.get_state_for_events() (and thus the existing stategroups) to
calculate the state corresponding to a particular sync position, rather than
state_handler.compute_event_context(), which recalculates from first principles
(and tends to miss some state).

Merged from PR https://github.com/matrix-org/synapse/pull/372

Basically this moves the process of flattening the existing dictionary into a
list up to rest.client.*, instead of doing it in handlers.sync. This simplifies
a bit of the code in handlers.sync, but it is also going to be somewhat
beneficial in the next stage of my hacking on SPEC-254.

Merged from PR #371

Add a couple of type annotations, docstrings, and other comments, in the
interest of keeping track of what types I have.

Merged from pull request #370.

Return non-room events from guest /events calls

Fix missing profile data in federation joins

Use a (hopefully) more efficient SQL query for doing recency based room search

There was a regression where we stopped including profile data in
initial joins for rooms joined over federation.

Changes to m.room.power_levels events are supposed to be handled at a high
priority; however a typo meant that the relevant bit of code was never
executed, so they were handled just like any other state change - which meant
that a bad person could cause room state changes by forking the graph from a
point in history when they were allowed to do so.

Merge pull request #367 from matrix-org/daniel/readafterleave

Tweak guest access permissions

Merge pull request #360 from matrix-org/daniel/guestroominitialsync

Allow guest access to room initialSync

 * Allow world_readable rooms to be read by guests who have joined and
   left
 * Allow regular users to access world_readable rooms