settings: Set a default index name for elasticsearch conns
jobs: Add timestamp fields to jobs model
search: Add updated_at field to SearchIndices

This allows the 'update_index' management command to only submit those
model objects modified within a specified timeframe to be reindexed. For
example,

    python manage.py update_index -a 2

will submit only those model objects updated in the past two hours to be
reindexed. This lightens the load on the search index, and reduces the
time spent updating the index.
search: Perform realtime index updates

Turning on the Haystack RealtimeSignalProcessor causes updates to the
search index to be made for models with appropriate on_save/on_delete
signals.

This increases the load associated with updating a model but I don't
foresee this causing any problems for us in the short term.

NB: As far as I can tell, django-cms pages are *not* automatically
updated by this mechanism, so we will additionally have to set up an
'update_index' cronjob.