Unbreak test - check for existence of headers.
Ensure the test .tgz files are not mangled by git.
Add etag support version, tgz resource get.

Also make new etag.js which handles setting ETag header on the response
and checking 'if-none-match' on the request.
Revert cache age back to 0.
Merge pull request #38 from CL0SeY/master

Keep the existing tests working after #37