Proxying of internally redirected files.
Fix AWS url signing to work with HEAD requests.
Use proxied file for genome browser visualization.
Fix correct paths in trackDb
Fixed the url's on browser
Avoid mutating the dict rendering html

It could be used somewhere else in the code leading to a sort of 'spooky action at a distance'.
Merge pull request #377 from ENCODE-DCC/1696-trackhub-aws

1696 trackhub aws