Adds details text box for eligibility to work

Please review this PR before: https://github.com/unepwcmc/unep-wcmc.org/pull/12

Changed the job applications' ability check bit to a Yes or No question with a field for details.
Now displaying the correct value for this field after submission. (previously was assuming that a boolean was being saved, but as it is being saved in a structure it's actually saving a string).

As a future improvement we might want to hide the details field if the answer is Yes.