Update remove-script-tags.js

Added .toString() to stringify the HTML being passed back by S3 when a page has been previously cached.
Merge pull request #29 from rmyock/master

Update remove-script-tags.js
Added HTML pretty print plugin
Merge branch 'master' of https://github.com/collectiveip/prerender
Added toString to comment stripping (see https://github.com/collectiveip/prerender/pull/29)
Adding pretty print plugin (forgot to add file)