App update

Submodule web/app 2b8aaf7..c2b049e:
  > Add the admin table summary page
  > Remove useless dict to dict conversion
  > Dynamic "Add new users" button depending upon the users list
  > Patch the add new user textarea ui
  > Rename the exercises_trainee_list sql installation file
  > Add the username_trainee_seq sequence to the database
  > Add the help page on how to add new users to the trainee list
  > Add the exercises_trainee_list table ddl
  > Add the basic page for the trainee listing
  > Add the navigation location in the trainer folder show page
  > Add the trainer username in the searchable field for admin on the exercise list page
  > Display the folder name in the folder show page