Typos in button labels

Below I'm attaching a patch with one typo fix and one suggested UI improvement. The latter is optional but I hope you'll take the typo fix.

This is a follow-up to #765540: Saving an existing node as draft will unpublish it which changed the text (rightly, I think) from "Save as Draft" for already-published nodes.

1. "Save as unpublish" changed to "Save as Unpublished" (capitalized to match the other button labels)
2. "Save Changes" changed to "Publish" (I think it's potentially confusing to people to have both "Save Changes" and "Save as Unpublished," especially on an already-created node they're editing.)

It's a pretty trivial patch, but I figured it'd be nicer to give you it instead of just asking you to change the text :)