Persist WP to disk to ensure it inherits hosts permissions

[kasparsd]

Fixes #26.

• Bind mount WP root to a local directory to ensure it inherits lower-level permissions of the host system instead of the default root used by named mounts.

[derekherman]

I'd prefer to remove all named volumes and create a data directory for this to live in like

- ./data/wordpress/html:/var/www/html

And also do this for mysql like

- ./data/mysql:/var/lib/mysql

The scripts for docker could be moved to /data/wordpress/config and /data/wordpress/Dockerfile. Then create a .gitignore inside the data directory with the following contents to allow for the data to be stored locally and have access to the filesystem.

*
!.gitignore
!wordpress/**
wordpress/html/*

And then update the build path build: ./data/wordpress