Require conformance to style standards

[thinkingserious]

Issue Summary

In the CONTRIBUTING.md file there is a section on Style Guidelines & Naming Conventions. Please review and implement a check in Travis CI. If there are any style errors, either fix or create a rule to exclude the error.

Before writing any code, we suggest you review our CONTRIBUTING.md file and propose your solution for discussion here in the comments. Thank you!

Aceptance Criteria

• TravisCI checks that the code conforms to our Style Guidelines & Naming Conventions as defined in our CONTRIBUTING.md file
• tests pass locally, in Travis CI and using Docker

[alanunruh]

@thinkingserious - I'll take this and implement the changes.