let mobile users include an email when submitting an issue report

http://manage.dimagi.com/default.asp?142086#edit_0_142086

![screen shot 2014-10-31 at 12 01 24 pm](https://cloud.githubusercontent.com/assets/1201876/4863878/0914b0e6-6118-11e4-8eb1-7804025a359d.png)

awaiting UI/UX signoff from @amsagoff