[#4]  Replacing local files by IQSets uploaded from iq-manager

This pull request fix this issue: https://github.com/SMILEConsortium/smile_teacher_android/issues/4

Bye bye local files, now prepared questions will have to be uploaded through smile-iqmanager before getting it on the teacher app. 
Image won't work for now.
Only large format is managed for the view.
The next is coming soon !