Fix ie7 validation ui bug

Available for testing on demo.

This branch:

* Reduces complexity by moving notice served validation into the model
* Fixes the spacing bug in IE7
* Fixes another bug where the "You must say whether or not you gave notice to the defendant" js-pseudo-validation was not added if the form was otherwise entirely correct

Things to check:

* Original spacing bug no longer manifests in IE7.
* Everyone is happy with the extra radio button on the non-js form

Things to consider:

* Does the "Was the defendant given notice to leave the property?" validation message make sense? It reads "You must say whether or not you gave notice to the defendant" (unchanged), but the actual validation is that the user has chosen "Yes".

The json does not need to have a "notice_served" value - as the PDF does not contain a "notice_served" field.

In practice the JSON only includes fields that are in the PDF template.