cli_tag, non-functional form drop-down, show tags on event detail page.

Version 1 implemented -- has cleaner error handline.

Added a 404.html template.
gracedb/view raises Http404 when event is not found.
Event.getByGraceId should now never return None.

Note that authorized followup user names are hardcoded into views.py

Only submitter can upload/log to an event.
Email alerts - removed file url.  Added event summary, which currently only includes GPS time.
Fixed bug where Omega event creation failed to add EventLog entries for event.log and coinc.xml.

Zero != None.  Now taking that into account.
Yes, it's a silly edge case, but if you enter zero
as a time, you should only get events with gps times, no?

Required mod in query view as well since "slop" != "end"

Required getting data out of ligolw tables.
Incidentally added processing of Omega results.

Adds new dependency on pylal for gwf reading and coinc table creation.
Relies on old dependency to glue for user code which does the above.

New model, EventLog.
Altered event "view" view and event_detail template to show log messages.

Changed uid to graceid, since it's not a uid.
Requires database change:
    ALTER TABLE gracedb_event DROP INDEX uid