Pycups

* cups.Connection.getJobAttributes()
* cups.Connection.cancelAllJobs()

* cups.Connection.getPrinterAttributes() now takes a uri keyword argument
for fetching attributes from non-CUPS IPP servers.

* cups.Connection.getDocument()
* cups.Connection.getDefault()

* IPP attribute strings are now represented as Unicode objects.

* cups.Connection.getDests() now includes a (None,None) key in its result
for identifying the default printer. This is intended to be equivalent
to cupsGetDest(NULL, NULL, ...).

* IPP attributes with type IPP_TAG_NOVALUE now take Python value None.