API: Error on bad meeting names, by default

When run from the command-line, make_meeting.py errors on bad meeting names
(eg, ones with newlines that could allow arbitrary code execution in the
aliases file).  That code was unfortunately not called in the ~API pathway, so
this fixes that.
Explicity ensure the remctl user has access
Make adding commands to make-meeting-wrapper easier
Add support for syncing read ACL from an AFS group
Produce reasonable-ish JSON responses

Note that this depends on a python-discuss version containing commit 122114cc2
("Raise an exception when meeting creation fails") to avoid unfortunate failure
modes on meeting creation failures.
JSONify AFS exceptions more reasonably
Log exceptions to syslog
Get tokens before doing AFS operations
Punt wayward klist