Fix task set creation and execution updates

Since the move to Rails 3.2.11, it hasn't been possible to create Task Sets or save changes to executions.  The culprit was passing the user object on to ActiveRecord rather than the user ID.  Old Rails versions used to convert that to 1, but new versions throw an error.  This discussion touches on the problem: http://stackoverflow.com/questions/13348980/activerecord-to-i-method-removed-in-rails-3-2-9