Pin to WP 3.8

This accurately pins WP to the correct Github release point of version 3.8
https://github.com/WordPress/WordPress/commit/36470a480cac07d34a355e9f8a9409c1349b6e07

The PR by @jcmendez points to commit c8eca4bf4ad7c1f9f0e05a99a73d5cc54d0b2573