Post box does not appear if settings are not saved

[benlk]

From one or our stations we are hearing:

Just updated to the Wordpress API plugin version that was just released and I do not have a box anywhere for NPROne. I have looked in the documentation and that box is not available on my screen or options. What happened?

Then from the same station:

Also noted. I have never had the API PUSH URL plugged in with the old version of the API plugin (http://api.npr.org). I found that if I set the Push URL and save that the NPROne box will appear in the story editor screen

• improve docs regarding this
• prompt in admin for manage_plugins users to save these settings, if not they are not saved.

[kaylima]

Acceptance criteria

• Plugin messages user if they try to engage with it unconfigured.
• Documentation/messaging in UI reviewed and accepted by Erin Teare and Janeen Williamson.