Probably swap jose for another jwe library

[ryanblock]

Over the last month during the run up to our big functions-python 1.0 release I swapped out jwcrypto for jose (python-jose). I made that choice in large part because jose had optional crypto backends, and did not necessitate use of the cryptography package. Later on I came to discover that for jwe encryption and decryption, jose does indeed require cryptography.

jose is a solid package, but is a bit out of date and no longer appears to be maintained, so we should evaluate some alternatives at our nearest convenience, absolutely including jwcrypto.