Revert "improvement of surveys"

This reverts commit 86de054c8a43fe12675e0029978f55c7cf10b132.
Improvement of surveys

-Created a javascript file called quvey.js which contains the scripts to
 handle the dynamic added of new questions.
-Modified survey controller to handle more correctly the creation of
 surveys.
-Modified datatype of field expired_at from survey table to datetime.
-Deleted unnecessary file _question_possible_value_fields.html.erb.
-Removed trailing spaces and added empty line to all files of project.
-Added to the spec create_survey the test about creation questions.