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/examples/subcommands.py b/examples/subcommands.py
index 4f569b1e..dd69d97e 100755
--- a/examples/subcommands.py
+++ b/examples/subcommands.py
@@ -7,6 +7,7 @@ This example shows an easy way for a single command to have many subcommands, ea
 and provides separate contextual help.
 """
 import argparse
+
 import cmd2
 
 sport_item_strs = ['Bat', 'Basket', 'Basketball', 'Football', 'Space Ball']