Include WP-CLI in all WordPress images

For a while now, WP-CLI has become the official way to manage WordPress from scripts / command line.

But if you glance through docker-entrypoint.sh, the current way of installing WordPress and hacking wp-config.php with sed and awk is not pretty and error-prone compared to a bunch of WP-CLI commands like

wp core download
wp config set
wp core install

WP-CLI doesn't take too much space, and it's become essential. I propose to:

• include WP-CLI in all official WordPress images,
• deprecate the stand-alone WP-CLI image,
• refactor docker-entrypoint.sh using WP-CLI.

It will show the community the relevant way of managing WordPress from the command line, and will make it easier to actually use the image later on. It will also solve #256.

Start with docker-entrypoint.sh and review how the current image installs WordPress and edits wp-config.php with sed and awk. Compare those steps with the proposed WP-CLI commands, then inspect how the standalone WP-CLI image is represented. Done means WP-CLI is included in all official WordPress images, the entrypoint uses it for setup, and the standalone image is deprecated.