Disable click event processing on attribute info buttons to prevent acci...

One of the first things I did when I interacted with the application was to click on the little grey information icons next to the attributes in the fieldPicker. This caused the app to both display a popover describing the field _and_ added the field to the fieldList. 

This pull request disables the click event on the grey information icons so that even if a user clicks (instead of hovering) they aren't surprised by having the field added to the fieldList.