Fix a bad loop scope bug in getKeysForNumber by using forEach.
Refactor the initial process of establishing key material for devices
that do not have open sessions.
// FREEBIE
It's rare that we get in a state where we have a device record without a
session, but we should handle errors gracefully in that case. Catch them
and register them, except for identity key errors which are registered
in handleResult.
// FREEBIE
fixup error handling // FREEBIE
This function dynamically declares a bunch of functions which bind to
its input arguments. Instead, use a new prototypal class to define
these functions within the context of a particular message.
// FREEBIE
