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, 2 insertions, 1 deletions

diff --git a/examples/exit_code.py b/examples/exit_code.py
index f4b19091..89ed86cd 100755
--- a/examples/exit_code.py
+++ b/examples/exit_code.py
@@ -2,9 +2,10 @@
 # coding=utf-8
 """A simple example demonstrating the following how to emit a non-zero exit code in your cmd2 application.
 """
-import cmd2
 from typing import List
 
+import cmd2
+
 
 class ReplWithExitCode(cmd2.Cmd):
     """ Example cmd2 application where we can specify an exit code when existing."""