Add more python functions in ion module

Ion.battery_level() return a int with the current battery level
Ion.battery_ischarging() return a bool with the current battery charging state
bugfix for upsilon

python/port/mod/os/modos.cpp

@@ -116,4 +116,4 @@ mp_obj_t modos_listdir(void) {
   }
   
   return list;
-}
+}