Buddy.py would try to subscribe to presence before the user had logged
in to whatsapp. A loginQueue was added, so that functions could be
deferred to login.
The names of groupchats are truncated internally to 22 characters.
This causes many problems with groupchats, since spectrum incorrectly
identifies the chat by the long name.
To overcome this the phoneNumber-unixTime is converted to hexadecimal,
to shorten the groupchat below 22 characters
