Added info on semantic versioning and branching strategy to CONTRIBUTING.md

Also:
- Added isort to Pipenv dev
- Added setup.cfg to make it easy to run flake8, doc8, and isort directly from the command line without using invoke
- Ran isort to sort includes

1 files changed, 1 insertions, 0 deletions

diff --git a/setup.py b/setup.py
index 860459a8..1da7f6c0 100755
--- a/setup.py
+++ b/setup.py
@@ -4,6 +4,7 @@
 Setuptools setup file, used to install or test 'cmd2'
 """
 import codecs
+
 from setuptools import setup
 
 DESCRIPTION = "cmd2 - quickly build feature-rich and user-friendly interactive command line applications in Python"