Update /php directory to be more descriptive

[rfearing]

Right now the /src/php directory gets copied to wp-content/themes/sparkpress within the docker instance.

We should update the directory structure to something like this (making sure to update scripts where needed).

└── src/
    ├── js/
    ├── php/
    ├── views/
    └── static/
         ├── images/
         └── style.css

Locations to consider:

• npm start script
• docker-compse.yml