Fix #490, #452, #431, and other things

[irskep]

• warn when *_PROTOCOL is a non-class #490: warn when *_PROTOCOL is a non-class
• Print job flow ID to stderr on error #452: Print job flow ID to stderr on error
• combine_cmds: shlex.split() doesn't get along well with unicode #431: combine_cmds: shlex.split() doesn't get along well with unicode

As well as:

• Fix $HADOOP_HOME test case to pass if you haven't set $HADOOP_HOME on the test machine
• tests.quiet.no_handlers_for_logger correctly restores the propagate attribute, resulting in less log noise