Interface implementation hooks

[Christopher Allan Webber]

Sometimes we want people to supply an alternate interface to "swap out" certain things. For example, they might want a totally different user authentication system, and maybe we'd have some sort of user authentication api.

Altenately, the storage interface is a good example.

In this method we set up a minimal interface and a default implementation. Users then have the option to swap out this implementation.

I think the way storage interfaces look are already currently pretty good, so swapping out the interface could probably be like:

  pluginapi.set_component('public_storage', BagOfHolding())

[Christopher Allan Webber]

It turns out with hook_handle there's no need to add additional tooling to this, but I documented a nice way of using interfaces via our tooling in commit 9d881aeeb4df2e9f02c4c1fea7d6435273081fdb!