More admin improvements:
* added created_by column to Tag list
* added columns to User table to show what tags the user is interested
  in, wants to ignore, and is subscribed to
* allow searching by object_id in Activity list
* show UserProfile in admin
Fixed bug in debug where 'message' is not a string, plus include a
timestamp in the message.
Fixes to send_email_alerts to ensure that:
* an user is always processed by the correct site
* we handle unexpected exceptions by emailing the exception details and
  the username to the admin, and then continuing on to the next user
* also, for now, lets print detailed logs for all users, not just
  WaterAid
Merge pull request #247 from knowledgepoint-devs/modal

Committing tested local changes from live server (fixes for ensuring that an user is always processed by the correct site, fixes debug(message) when message is not a string), plus general exception handling, and admin improvements.