please tag when doing a npm publish

[kapouer]

A simple way to do that is npm version 4.2.0.
However, now that many tags are missing, it would be nice to just have the last one:

git tag v4.2.0 f8e1944b

this will make bisecting bugs, and also redistribution of your software, easier.

[metafloor]

The tagging of releases broke when github changed the authentication api (v3.0.1 was the last tagged release). Will try to make fixing the release script a priority for the next iteration - which will likely be syncing to the latest BWIPP release.