adding a new anonymous participant on top of the drop down so if the user does nothing, that participant is used and saved

for https://github.com/ProjetDeRechercheSurLecriture/DyslexDisorthGame/issues/186
creating participant details component for https://github.com/ProjetDeRechercheSurLecriture/DyslexDisorthGame/issues/186
not creating participant in the experiment, expecting a participant select will do it.
adding sails fields to the corpus for https://github.com/ProjetDeRechercheSurLecriture/DyslexDisorthGame/issues/186
url indicates which db youre saving to
not displaying previous participants when in the demo database