fix an issue deploying 0.15 to the web store, and fail the build when we...

Fix an issue deploying 0.15 to the web store (for now, we do need the longer version string), and fail the build when we can't deploy (return the failure message from the web store).

@ussuri, TBR to see if it does deploy to the web store
So, `publishItem` and `uploadItem` are 95% the same - we should factor out the common part.