Do a better job of categorizing field types in the JSON field map

[bengolder]

Currently:

• a checkbox is indicated by "type": "button", and "options": ["Yes", "Off"]
• a set of radio options are indicated by "type": "button" and 2 or more "options" in addition to "Off"
• a text field is "type": "text"
• dropdowns and listboxes are both "type": "choice"

Perhaps for checkboxes and radio buttons, they should be "type": "checkbox" and "type": "radio" since those two types are easy to infer from the field data output.