Fix event-purge-by-ts admin API

Fix federation backfill from sqlite servers

Make sure that attr is installed

This got completely broken in 0.30.

Fixes #3300.

We've rcently added a dep on `attr`. I don't know why the CI didn't pick this
up, but we should make it explicit anyway.

If this was called with a `(type, None)` entry in types (which is supposed to
return all state of type `type`), it would explode with a sql error.

Changes in synapse v0.31.0 (2018-06-06)
======================================

Most notable change from v0.30.0 is to switch to python prometheus library to improve system
stats reporting. WARNING this changes a number of prometheus metrics in a
backwards-incompatible manner. For more details, see
`docs/metrics-howto.rst <docs/metrics-howto.rst#removal-of-deprecated-metrics--time-based-counters-becoming-histograms-in-0310>`_.

Bug Fixes:

* Fix metric documentation tables (PR #3341)
* Fix LaterGuage error handling (694968fa)
* Fix replication metrics (b7e7fd2d)

Changes in synapse v0.31.0-rc1 (2018-06-04)
==========================================

Features:

* Switch to the Python Prometheus library (PR #3256, #3274)
* Let users leave the server notice room after joining (PR #3287)

Changes:

* daily user type phone home stats (PR #3264)
* Use iter* methods for _filter_events_for_server (PR #3267)
* Docs on consent bits (PR #3268)
* Remove users from user directory on deactivate (PR #3277)
* Avoid sending consent notice to guest users (PR #3288)
* disable CPUMetrics if no /proc/self/stat (PR #3299)
* Add local and loopback IPv6 addresses to url_preview_ip_range_blacklist (PR #3312) Thanks to @thegcat!
* Consistently use six's iteritems and wrap lazy keys/values in list() if they're not meant to be lazy (PR #3307)
* Add private IPv6 addresses to example config for url preview blacklist (PR #3317) Thanks to @thegcat!
* Reduce stuck read-receipts: ignore depth when updating (PR #3318)
* Put python's logs into Trial when running unit tests (PR #3319)

Changes, python 3 migration:

* Replace some more comparisons with six (PR #3243) Thanks to @NotAFile!
* replace some iteritems with six (PR #3244) Thanks to @NotAFile!
* Add batch_iter to utils (PR #3245) Thanks to @NotAFile!
* use repr, not str (PR #3246) Thanks to @NotAFile!
* Misc Python3 fixes (PR #3247) Thanks to @NotAFile!
* Py3 storage/_base.py (PR #3278) Thanks to @NotAFile!
* more six iteritems (PR #3279) Thanks to @NotAFile!
* More Misc. py3 fixes (PR #3280) Thanks to @NotAFile!
* remaining isintance fixes (PR #3281) Thanks to @NotAFile!
* py3-ize state.py (PR #3283) Thanks to @NotAFile!
* extend tox testing for py3 to avoid regressions (PR #3302) Thanks to @krombel!
* use memoryview in py3 (PR #3303) Thanks to @NotAFile!

Bugs:

* Fix federation backfill bugs (PR #3261)
* federation: fix LaterGauge usage (PR #3328) Thanks to @intelfx!

Redact AS tokens in log (fixes to #3327)

update tox.ini to cover 292 succeeding tests

federation/send_queue.py: fix usage of sortedcontainers.SortedDict

Signed-Off-By: Matthias Kesler <krombel@krombel.de>

Strip `access_token` from outgoing requests

doc/postgres.rst: fix display of the last command block

Also indent all of them with 4 spaces.

Remove was_forgotten_at

Cache factor override system for specific caches

fix bug introduced in #3256

federation: fix LaterGauge usage

Fixes a startup crash due to commit df9f72d9
"replacing portions".

This is unused. IT MUST DIE!!!1
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