feedback_reviews model didn't have any attr_accessible

I was getting an error on creating a feedback rating because mass assignment wasn't setup.

Signed-off-by: Nathan Lowrie <nate@finelineautomation.com>
Fixed a missing translation error.

Signed-off-by: Nathan Lowrie <nate@finelineautomation.com>
A user can't rate a review more than once.

Added a validation and also take away the ability to enter feedback on the form if they've already entered it.

Signed-off-by: Nathan Lowrie <nate@finelineautomation.com>
Cleaned up the specs a bit.

Signed-off-by: Nathan Lowrie <nate@finelineautomation.com>