Delay the upload of one-time keys until we have received a sync *without any
to-device messages*. Doing so means that we can try to avoid throwing away our
private keys just before we receive the to-device messages which use them.
Once we've decided to go ahead and upload them, we keep uploading them in
batches of 5 until we get to the desired 50 keys on the server. We then
periodically check that there are still enough on the server.
89ced198 added some code which flagged our own device list as in need of an
update. However, 8d502743 then added code such that we invalidate *all* members
of e2e rooms on the first initialsync - which should include ourselves. We can
therefore remove the redundant special-case, which mostly serves to simplify
the tests.
Much of this transformation has been done automatically:
* add expect import to each file
* replace `not.to` with `toNot`
* replace `to[Not]Be{Undefined,Null}` with equivalents
* replace `jasmine.createSpy(...)` with `except.createSpy`, and `andCallFake`
with `andCall`
Also:
* replace `jasmine.createSpyObj` with manual alternatives
* replace `jasmine.Clock` with `lolex`
