use random.choice for compat with python3.5

sshshare_ws/endpoints.py

@@ -36,7 +36,9 @@ class ShareStoreAPI(Resource):
         value = json.dumps(postdata)
         logger.debug("post value {}".format(value))
         while not acceptedkey:
-            key = ''.join(random.choices(string.ascii_uppercase + string.digits, k=16))
+            key = ''
+            for i in range(0,16):
+                key=key+random.choice(string.ascii_uppercase + string.digits)
             try:
                 newsd = ShareData(key=key,value=value)
                 db_session.add(newsd)