Tests: get rid of classes in test files.

Class usage came from the unittest framework and it was always redundant
after migration to the pytest.  This commit removes classes from files
containing tests to make them more readable and understandable.

test/unit/applications/websockets.py

@@ -6,12 +6,12 @@ import select
 import struct
 
 import pytest
-from unit.applications.proto import TestApplicationProto
+from unit.applications.proto import ApplicationProto
 
 GUID = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"
 
 
-class TestApplicationWebsocket(TestApplicationProto):
+class ApplicationWebsocket(ApplicationProto):
 
     OP_CONT = 0x00
     OP_TEXT = 0x01