Optimistic Locking ...

- add bit field to question_format so we don't have to test strings to determine format

- add isOptionBased to question so we dn't have to do multiple string comps for this - there was a boolean already in the DB not being used

- add migration to add bit field

- add migration to add lock_version field to answer

- change answers_controller to do optimistic locking

- change answers controller not to redirect to plans/phase/edit as it wasn't doing anything

- introduced answers/update.js.erb to handle the return from /answers/update.

- to do the conflict resolution you need the old answer and new answer objects. Tried using clone but it doesn't work because it only does a shallow copy. So adopted a "nuclear-option" deep copy but it's a bit much. A compromise would be better.