pylint: Update pylint to 1.7.1, run on tests/ and tools and fix complaints.

The motivation for this is that
 a.) 1.7.1 runs with python 3.6 (bionic)
 b.) we want to run pylint on tests/ and tools for the same reasons
     that we want to run it on cloudinit/

The changes are described below.
- Update tox.ini to invoke pylint v1.7.1.
- Modify .pylintrc generated-members ignore mocked object members (m_.*)
- Replace "dangerous" params defaulting to {}
- Fix up cloud_tests use of platforms
- Cast some instance objects to with dict()
- Handle python2.7 vs 3+ ConfigParser use of readfp (deprecated)
- Update use of assertEqual(<boolean>, value) to assert<Boolean>(value)
- replace depricated assertRegexp -> assertRegex
- Remove useless test-class calls to super class
- Assign class property accessors a result and use it
- Fix missing class member in CepkoResultTests
- Fix Cheetah test import

1 files changed, 5 insertions, 2 deletions

diff --git a/tests/unittests/test_distros/test_create_users.py b/tests/unittests/test_distros/test_create_users.py
index aa13670a..5670904a 100644
--- a/tests/unittests/test_distros/test_create_users.py
+++ b/tests/unittests/test_distros/test_create_users.py
@@ -7,7 +7,11 @@ from cloudinit.tests.helpers import (TestCase, mock)
 class MyBaseDistro(distros.Distro):
     # MyBaseDistro is here to test base Distro class implementations
 
-    def __init__(self, name="basedistro", cfg={}, paths={}):
+    def __init__(self, name="basedistro", cfg=None, paths=None):
+        if not cfg:
+            cfg = {}
+        if not paths:
+            paths = {}
         super(MyBaseDistro, self).__init__(name, cfg, paths)
 
     def install_packages(self, pkglist):
@@ -42,7 +46,6 @@ class MyBaseDistro(distros.Distro):
 @mock.patch("cloudinit.distros.util.subp")
 class TestCreateUser(TestCase):
     def setUp(self):
-        super(TestCase, self).setUp()
         self.dist = MyBaseDistro()
 
     def _useradd2call(self, args):