(P) Main
   -> If login not detected, automatically goes to:
       (P) Startup
           (P) Sign up, has these ContentViews as registration steps:
               (V) Email and password
               (V) Name
               (V) Profile photo
                   -> Call to CrossMedia.Current.TakePhotoAsync
               (V) Other details
                   -> Returns to Main, if has successful profile creation.
           (P) Sign in
               -> Returns to Main, if has successful login.
   -> If login detected:
        -> Load the content of the Main page.