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/proto.py

@@ -1,10 +1,10 @@
 import os
 
-from unit.control import TestControl
+from unit.control import Control
 from unit.option import option
 
 
-class TestApplicationProto(TestControl):
+class ApplicationProto(Control):
     application_type = None
 
     def get_application_type(self):