fix(rxModalAction): no longer destroys scope.fields on modal submit

BREAKING CHANGE: 'fields' property no longer checks if scope.fields is already defined.
If you're defining 'fields' information inside the modal pre-hook, everything should work as normal
If you're defining it before the pre-hook (on page load), this will break. You will need to move that definition into a pre-hook function
Merge pull request #141 from rackerlabs/fix-modal-option-table

fix(rxModalAction): no longer destroys scope.fields on modal submit