Advanced Custom Fields shouldn't be bundled with the theme

[craigcook]

Bundling third-party plugins usually causes more problems than it solves. Updating it has to be done manually, which makes it an ongoing maintenance burden (or it just grows further and further out of date because nobody will maintain it by hand). It can also wreak havoc if someone were ever to enable the regular plugin. The way to avoid that is to painstakingly rename everything that might conflict with the regular plugin, and in that case we're just forking and modifying the code and making it even harder to maintain.

So let's work on debundling ACF and using the separate plugin instead.

In general, plugins should be treated as optional since they can always be disabled or removed, even by accident, and that can take the whole site down. We can require ACF for the enhanced functionality it gives us, but we can build in some basic checks to avoid errors if it's disabled and still offer readable content as a fallback.

[slightlyoffbeat]

@craigcook I have a PR that addresses this. It removes ACF, and provides a fallback if it isn't installed.

https://github.com/slightlyoffbeat/foxtail/pull/16