Suggestion - update Continuous integration section to include basic yaml file

[pgryko]

Location within the Book

• Chapter 32: Continuous integration and Chapter 3.3 Makefiles/Fabric

Description

Provide an example .yaml file for building an docker container and running within travis-ci/gitlab-ci. The yaml files are quite short .e.g

language: python
python:

• "2.7"
• "3.3"
• "3.4"
• "3.5"
• "3.6"

command to install dependencies

install:

• pip install -r requirements.txt

command to run tests

script:

• pytest # or py.test for Python versions 3.5 and below

I would also suggest updating the Chapter 3.3 Makefiles/Fabric to use .yaml to match what the CI & docker descriptions you have.