[#23] Reverting buttons and checkboxes

Relative issue: 
#23
https://github.com/RazortoothRTC/node-smile-server/issues/42

Reverting buttons to initial state, uncheck checkboxes of students, dropping ratings and answers
Retake button looks good on teacher app now.
I still need to update the variable SMILESTATE in node-smile-server >> smilestudent.js but I don't really know how this variable is updated