Enable flake8 checks

This commit enables new flake8 checks:
* E265  block comment should start with '# '
* H405  multi line docstring summary not separated with an empty line
* E123  closing bracket does not match indentation of opening bracket's line
* H238  old style class declaration, use new style (inherit from `object`)
* E128  continuation line under-indented for visual indent
and makes related changes in the code.

Change-Id: Ie993afc930f6b74d7a990bcaa9fc0e9f5ba1585c

glanceclient/tests/unit/v2/test_shell_v2.py

@@ -30,11 +30,11 @@ class ShellV2Test(testtools.TestCase):
         self.gc = self._mock_glance_client()
 
     def _make_args(self, args):
-        #NOTE(venkatesh): this conversion from a dict to an object
+        # NOTE(venkatesh): this conversion from a dict to an object
         # is required because the test_shell.do_xxx(gc, args) methods
         # expects the args to be attributes of an object. If passed as
         # dict directly, it throws an AttributeError.
-        class Args():
+        class Args(object):
             def __init__(self, entries):
                 self.__dict__.update(entries)