API changes and complete API documentation (#61)

* SampleSheetSection are now case insensitive and act like dicts

* First time doctesting tutorial

.pre-commit-config.yaml

@@ -0,0 +1,6 @@
+repos:
+-   repo: https://github.com/ambv/black
+    rev: stable
+    hooks:
+    - id: black
+      language_version: python3.6

README.md

@@ -1,12 +1,13 @@
 # sample-sheet
 
 [![PyPi Release](https://badge.fury.io/py/sample_sheet.svg)](https://badge.fury.io/py/sample_sheet)
+[![Python Versions](https://img.shields.io/pypi/pyversions/sample-sheet.svg)](https://pypi.python.org/pypi/sample-sheet/)
+[![License](https://img.shields.io/pypi/l/sample-sheet.svg)](https://github.com/clintval/sample-sheet/blob/master/LICENSE)
 [![Testing Status](https://travis-ci.org/clintval/sample-sheet.svg?branch=master)](https://travis-ci.org/clintval/sample-sheet)
 [![Documentation Build Status](https://readthedocs.org/projects/sample-sheet/badge/?version=latest)](https://sample-sheet.readthedocs.io/en/latest/?badge=latest)
 [![Code Coverage](https://codecov.io/gh/clintval/sample-sheet/branch/master/graph/badge.svg)](https://codecov.io/gh/clintval/sample-sheet)
 [![MyPy Checked](http://www.mypy-lang.org/static/mypy_badge.svg)](http://mypy-lang.org/)
-[![License](https://img.shields.io/pypi/l/sample-sheet.svg)](https://github.com/clintval/sample-sheet/blob/master/LICENSE)
-[![Python Versions](https://img.shields.io/pypi/pyversions/sample-sheet.svg)](https://pypi.python.org/pypi/sample-sheet/)
+[![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/ambv/black)
 
 An open source library to completely replace [Illumina's Experiment Manager](https://support.illumina.com/sequencing/sequencing_software/experiment_manager.html).
 

docs/CONTRIBUTING.md

@@ -12,7 +12,7 @@ The complete test suite is configured through `Tox`:
 
 List all environments with:
 
-```bash
+```
 ❯ tox -av
 using tox.ini: .../sample-sheet/tox.ini
 using tox-3.1.2 from ../tox/__init__.py