refactor management api in order to use view function in place of method view.
refactoring of profile api in the frame of the pull request #1
refactoring from MethodView to view function done. tests adapted due to the API modifications. Everything is green!
post positions for a profile
append positions informations (percentage, count, url) in response for profile
tests for  assignment of positions to profiles written and executed
tests for deletion of assignment of positions to profiles written and executed