This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
As it stands we load up user records quite frequently on the topic pages,
this in turn pulls all the columns for the users being selected, just to
discard them after they are loaded
New structure keeps all options in a discrete table, this is better organised
and allows us to easily add more column without worrying about bloating the
user table
There were actually 2 bugs:
1/ Calling '.try(:key)' on a hash doesn't work. So EmailLogs were never associated to a user.
2/ Turns out that we update the 'user.last_emailed_at' whenever we create an EmailLog (in the 'after_create' callback).
So we need to always create an EmailLog (whenever the email is sent or skipped).
