Hygiene: Use accept attribute in uploads file input tag

This change removes irrelevant options in the Android dialog that asks
for the app that should handle the file input. Previously Android would
display all apps, including the ones that can't be used to select images
(e.g. music related).

Tested on Android Browser 4.1 and 4.2 and it works fine, you can use
camera. We don't support uploads on Android < 4.

Change-Id: I61e056823ff3e82209de483d6d974fef3fcf672c
Merge "Hygiene: Use accept attribute in uploads file input tag"