"Set" formfield: Make sure checkbox is behind pseudo-checkbox

Currently:
![screen shot 2014-08-14 at 13 59 52](https://cloud.githubusercontent.com/assets/360800/3919608/2160a3f8-23ab-11e4-8644-714adae9cefd.png)

This leads to problematic usability on some Android phones browsers (confirmed on our Galaxy SII and HTC). It seems the *click on the label* doesn't work reliably there, so the user needs to click on the actual checkbox. If this is displaced, then hitting it is obviously difficult.

cc @moby86