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/Pipfile b/Pipfile
index 5d23fcf0..e03fc25d 100644
--- a/Pipfile
+++ b/Pipfile
@@ -18,6 +18,7 @@ flake8 = "*"
 gnureadline = {version = "*",sys_platform = "== 'darwin'"}
 invoke = "*"
 ipython = "*"
+isort = "*"
 mock = {version = "*",markers = "python_version < '3.6'"}
 plumbum = "*"
 pyreadline = {version = "*",sys_platform = "== 'win32'"}