I've added some Documentation, how to get the running Version of a
Synapse homeserver. This should help the HS-Owners to check whether the
Upgrade was successful.

Allow clients to upload one-time-keys with new sigs

Change register/available to POST (from GET)

might help us figure out if https://github.com/vector-im/riot-web/issues/3868
has happened.

When a client retries a key upload, don't give an error if the signature has
changed (but the key is the same).

Fixes https://github.com/vector-im/riot-android/issues/1208, hopefully.

Don't update event cache hit ratio from get_joined_users

Cache check to see if device exists

Cache one time key counts

Otherwise the hit ration of plain get_events gets completely skewed by
calls to get_joined_users* functions.

Revert speed up push

This reverts commit ab37bef8.

This reverts commit ad8b3169.

This reverts commit 421fdf74.

Always mark remotes as up if we receive a signed request from them

	Handle exceptions thrown in handling remote device list updates

Rewrite SimpleHttpClient.request to include timeouts 

Make get_joined_users faster

Fixes #2191

Optimise caches for single key