fix to search for geojson instead of txt

Author: Alan D. Snow

tethysapp/streamflow_prediction_tool/controllers.py

@@ -306,7 +306,7 @@ def get_watershed_layers_info(a_watershed_list):
                 available_forecast_dates = \
                     available_forecast_dates + \
                     get_ecmwf_valid_forecast_folder_list(
-                        path_to_watershed_files, ".txt")
+                        path_to_watershed_files, ".geojson")
 
         watershed_layers_info_array = get_watershed_layers_info(watersheds)[0]