refactored statistics so that they are loaded by the statistics service and then resolved the collections bug

added security check that checks if user can see the exercise he is liking and added an index on exercise_id to likes table

progress bar dispalys numbers now, trophy beside progress bar to see what kind of challenge the user is doing, reordered tropies, added disclaimer if no trophy has been achieved or if all trophies have been achieved, improved sql query to get both results at once, improved layout