Adding support for prerender token, fixing compatibility with later versions of prerender so the status code (and headers) returned from prerender service are correctly put onto the response back to the crawler, and the pipeline is terminated. Also improved crawler detection by using contains rather than exact case insensitive match. Finally, added support for AWS load balancers with use X-Forwarded-Proto headers
Merge pull request #1 from mgoodfellow/master

Adding support for prerender token, fixing compatibility with later versions of prerender