Currently we're flipping the radio in "MMS" mode, and connecting through
any proxies specified in the APN. This always work, or at least doesn't
seem to work on Sprint, since the configured mms proxy rejects proxy
requests.
Instead we try the following in this order:
1) Connect over normal data connection directly to MMSC.
2) Connect over MMS radio connection to MMSC.
3) Connect over MMS radio connection with any configured proxy to MMSC.
Hopefully this doesn't fuck up shit on other unknown networks.
1) If a message fails to be delivered, post a notification in the
status bar if that thread is not active and visible.
2) If a message fails to be delivered because there is no service,
keep retrying every time service becomes available again.
1) Refactor recipient class to support asynchronous loading operations.
2) Refactor recipient factory to simplify recipient access.
3) Consoliate everything into one recipient provider that is capable of
doing async lookups and intelligent caching.
