We were too permissive with slugs

We allowed apostrophes in slugs, which caused problems downstream. We should not have to escape the values in a slug.

It looks like node-slug is not actively maintained. There's a fork with some fixes, but the node-slugs module (note the "s") uses a whitelist (`\w` regular expression special character plus a configurable array of allowed characters), which makes me much more comfortable.

/cc @hampelm