Updates to handle some XMPP protocol changes

DS-
Documented at https://developers.google.com/cloud-print/docs/rawxmpp

This is reported to address #48. I don't have confirmation of that.
no problems encountered in testing.
Add -f 'fast poll' option - mitigate XMPP failure

Some are reporting a persistent problem with XMPP notifications:

https://github.com/armooo/cloudprint/issues/48 - Issue #48

The problem is persistent, and is not related to networking issues.

This is an admitted hack to provide a workaround for that case.
Invoking the '-f' command line argument causes the print queues to
be polled every 30 seconds.
Merge pull request #65 from davesteele/fast_poll

Add -f 'fast poll' option - mitigate XMPP failure
Merge pull request #66 from davesteele/protocol_update

Updates to handle some XMPP protocol changes