Fix 'enter' in autocomplete fields (reviewboard)
Handling of the 'enter' key for autocomplete fields like people and groups

wasn't correct, because the djblets handler (which submits the field) was

running before the autocomplete handler (which populates the field with the

current selected item).
The fix is to ensure that the keydown handlers run in the other order. This

change does the review board side of that, using the new 'deferEventSetup'

option to avoid connecting the events until after we set up autocomplete.

Reproduced the bug. After this fix (and the matching reviewboard one), I can

press "enter" with a selected user and it will properly populate the field.