Require email verify. As of now we don't have the "verified" bit in the storage layer so it passes. Once we put that in, we'll have to go back and add a call to the verification endpoint.
* Regress from `lastSynced` to just `sequence` to start with something simpler
* Simplified payload: separate metadata, assume canonical way to hmac it together
* No more "wallet state" except as a simple wrapper on the front end
* Version number in wallet payloads
A few things at once because it was faster to get a demo out the door. Skipping most test implementation though I made failing stubs so I know what to fill in later.
* Get/Post WalletState
* downloadKey/email so that a second client can log in, and/or recover from lost client
* Test client in Python to demonstrate the above
* Organize into packages
