Aborted attempt to get AES working for pickles.

Walking away for now, because the openssl code is not stable, it
is prone to hanging and I am not sure why. The openssl code needs
to be rewritten anyway to support data streams, buffering everything
up in RAM is just asking for trouble.
Moved mailboxes out of mailutils.py
Moving crypto code into mailpile.crypto
Teach decrypt_and_parse_lines to preserve newlines if requested
More graceful shutdown on errors
Handle binary data in encrypted content a bit better
Added the ability to edit messages from the command-line (shells out to editor)