Make plugins more testable

[vrv]

Right now, actions that require authentication through our actions_v0 module are a bit challenging to mock out, though it's possible. We should implement a way to make all of our plugins testable in isolation.

In cases where the plugin implementation only needs authentication for some resources, the test can use public resources if actions_v0 is mocked out properly. In cases where the plugin implementation requires authentication, we might want a mechanism for a user to authenticate locally to test things.