[py2to3] Refactor gluster_base_class.py

Following changes were implemented:
- Delete unused imports and place used ones in the alphabetical order.
  Imports are splitted into 3 groups: built-ins, third-parties and
  local modules/libs.
- Make changes to support py3 in addition to py2.
- Minimize number of code lines keeping the same behaviour and improving
  readability.
- Add possibility to get 'bound' (cls) methods using 'get_super_method'
  staticmethod from base class. Before it was possible to call only
  unbound (self) methods.
- Update 'test_add_brick.py' module as PoC for running base class bound
  methods in both - py2 and py3. Now this module py2/3 compatible.

Change-Id: I1b66b3a91084b2487c26bec8763ab2b4e12ac482
Signed-off-by: Valerii Ponomarov <kiparis.kh@gmail.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/functional/glusterd/test_add_brick.py b/tests/functional/glusterd/test_add_brick.py
index c802c79be..b8646098d 100644
--- a/tests/functional/glusterd/test_add_brick.py
+++ b/tests/functional/glusterd/test_add_brick.py
@@ -33,7 +33,7 @@ class TestVolumeCreate(GlusterBaseClass):
     def setUpClass(cls):
 
         # Calling GlusterBaseClass setUpClass
-        GlusterBaseClass.setUpClass.im_func(cls)
+        cls.get_super_method(cls, 'setUpClass')()
 
         # check whether peers are in connected state
         if not cls.validate_peers_are_connected():
@@ -57,7 +57,7 @@ class TestVolumeCreate(GlusterBaseClass):
             raise ExecutionError("Failed to delete the brick dirs.")
         g.log.info("Successfully cleaned all the brick dirs.")
 
-        GlusterBaseClass.tearDown.im_func(self)
+        self.get_super_method(self, 'tearDown')()
 
     def test_add_brick_functionality(self):