App update

Submodule web/app 6c466b7..9c2ab24:
  > Button to create the exercises in PiAnoS
  > Refactoring of the pianos_update_all_accounts() function
  > Add the button to load the other page in the tenprint template page

app @ 9c2ab24d

-Subproject commit 6c466b7dab7a1d0eb00bf5e36260bba79394ab29
+Subproject commit 9c2ab24d7e6ff0c6a8f5954abeb145b6dd50b58b