App update

Submodule web/app 806ee88..9b07496:
  > Add the trainer username in the exercises list for administrators
  > For for the account type in the exercises list page (trainer or admin)
  > Add the exercise.sql ddl file
  > Update the mode of clean_sql_files.sh
  > Show only active exercises for the trainers
  > Order the exercises name asc
  > Add the function to rename a exercise by trainers
  > Use a table for the list of exercises for the trainer accounts
  > Add the search bar on the trainer exercise search page
  > Add all the exercises informations in the exercises.html page
  > Display the error if the exercise list can not be created
  > Refactoring of the mark search page
  > Add the basic exercise page for trainers (and add the function to create a new case in db)
  > Patch the dev environment (insensitive to the case)