Add Development Environment and Cypress sections to CONTRIBUTING.md

[captaindav]

Is your feature request related to a problem? Please describe. As a developer I would like to have documentation on using Cypress with Druxt and how to setup a development environment.

Describe the solution you'd like Add Cypress and Development environment info to CONTRIBUTING.md

[Decipher]

Adding to this, we are also planning on restructuring and updating the existing examples and documentation directory structure and content.