Listing to json conversion

I think this is ready to go now.
 - agreed with Tony R which security questions need to be converted to 'choose as many as apply' fields instead of 'choose one'
 - Dates now in standard format for validation at the API
 - Updated version number for post-switch-off releases
Hmm, yes, good spot.  I started off by using `gson.toJson` everywhere for exactly that reason, but then saw double-escaped values coming through.  This is because some of the values in the SSP are already JSON-escaped. So I ditched the toJson, but you're right that some of the fields will now break.  I'll review now and fix it up.