Fix bug json_save with save_json

PythonServer/pos-python-server.py

@@ -367,7 +367,7 @@ class epicsQuery(Thread):
                     instruments_return_dict[pv]['units']='n.c.'
                     instruments_return_dict[pv]['value']=''
 
-            json_save(instruments_return_dict, '/var/www/data/getInstruments.json')
+            save_json(instruments_return_dict, '/var/www/data/getInstruments.json')
             time.sleep(0.5)
 
         for pv in publicpvs: