Bump node-slideshare github revision

Pretty sure SlideShare stopped accepting HTML bodies in GET requests all of a sudden, and the slideshare units are now broken for me. I've submit a PR to our node-slideshare parent clone, but have cloned an oaeproject repo in the meantime with this commit: https://github.com/oaeproject/node-slideshare/commit/137858c7d83df4ba2f7202266b36bdc41fac35bb