Enable global hacking checks and removed local checks

In this patchset, I set up 'enabled-extensions' in flake8 section
of tox.ini. In newer hacking versions, we can enable some of the
non-default hacking rules (one by one), which are disabled by default
and implemented in the newer versions of hacking. The enabled extensions
are the following:

* [H106] Don’t put vim configuration in source files (off by default).
* [H203] Use assertIs(Not)None to check for None (off by default).
* [H904] Delay string interpolations at logging calls (off by default).

Together with enabling these rules, I also removed the locally
implemented versions of them. Due to limitations of local checking
engine, there were some places in the tests, where pep8 failed.

In this patchset, these codes are also fixed.

Change-Id: I3a9d2dc007a269cdb2cad441e22f5eb9b58ce0a0

HACKING.rst

@@ -21,13 +21,10 @@ Nova Specific Commandments
   should be moved into a common module
 - [N313] capitalize help string
   Config parameter help strings should have a capitalized first letter
-- [N314] vim configuration should not be kept in source files.
 - [N316] Change assertTrue(isinstance(A, B)) by optimal assert like
   assertIsInstance(A, B).
 - [N317] Change assertEqual(type(A), B) by optimal assert like
   assertIsInstance(A, B)
-- [N318] Change assertEqual(A, None) or assertIs(A, None) to optimal assert
-  like assertIsNone(A)
 - [N319] Validate that debug level logs are not translated.
 - [N320] Setting CONF.* attributes directly in tests is forbidden. Use
   self.flags(option=value) instead.
@@ -64,7 +61,6 @@ Nova Specific Commandments
 - [N351] Do not use the oslo_policy.policy.Enforcer.enforce() method.
 - [N352] LOG.warn is deprecated. Enforce use of LOG.warning.
 - [N353] Validate that context objects is not passed in logging calls.
-- [N354] String interpolation should be delayed at logging calls.
 - [N355] Enforce use of assertTrue/assertFalse
 - [N356] Enforce use of assertIs/assertIsNot
 - [N357] Use oslo_utils.uuidutils or uuidsentinel(in case of test cases) to

tox.ini

@@ -161,6 +161,7 @@ commands = bash -c tools/releasenotes_tox.sh
 #
 # E251 Skipped due to https://github.com/jcrocholl/pep8/issues/301
 
+enable-extensions = H106,H203,H904
 ignore = E121,E122,E123,E124,E125,E126,E127,E128,E129,E131,E251,H405
 exclude =  .venv,.git,.tox,dist,doc,*lib/python*,*egg,build,tools/xenserver*,releasenotes
 # To get a list of functions that are more complex than 25, set max-complexity