Update references to page cache in brand plugins when moving this repo to the new GitHub org

[wpscholar]

This repo is directly referenced in all of our brand plugins. When moving this repo to the new GitHub org, we need to make sure all of these get updated.

Bluehost:
https://github.com/bluehost/bluehost-wordpress-plugin/blob/master/inc/performance.php#L41

HostGator:
https://github.com/bluehost/wp-plugin-hostgator/blob/b948fc39715a56618395fbbeb4393f10c1f78c1b/inc/performance.php#L57

Web.com:
Doesn't exist at the time this issue was created.