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, 1 insertions, 1 deletions

diff --git a/tools/make-mime.py b/tools/make-mime.py
index f6a72044..d321479b 100755
--- a/tools/make-mime.py
+++ b/tools/make-mime.py
@@ -23,7 +23,7 @@ def file_content_type(text):
         filename, content_type = text.split(":", 1)
         return (open(filename, 'r'), filename, content_type.strip())
     except ValueError:
-        raise argparse.ArgumentError("Invalid value for %r" % (text))
+        raise argparse.ArgumentError(text, "Invalid value for %r" % (text))
 
 
 def main():