(Group) add ability to set appearance attribute to field-list

Does this: https://confluence.dimagi.com/display/commcarepublic/Common+Logic+and+Calculations#CommonLogicandCalculations-DisplayingQuestionsinListForm(forAndroidonly)

![screen shot 2013-06-27 at 5 17 48 pm](https://f.cloud.github.com/assets/716573/718855/109b69a8-df6f-11e2-898a-b79af74b740c.png)