Use another-json instead of awful manual json building. Sign the device keys at
the point of upload, instead of having to keep the signed string in
memory. Only upload device keys once (they are correctly merged with the
one-time keys by synapse).
Starts work on a class which is intended to just wrap the Matrix apis with very
simple functions.
There is a lot more work to be done here. For now, I have just taken methods
which don't refer to anything in MatrixClient except _http. This excludes a
bunch of things which refer to $userId, as well as the login stuff because of
the deviceId stuff I've just added :/.
For now, it's an internal class. I don't really see any reason it can't be
exposed to applications, though.
