Fix bugs
Fix bugs

1. change variable name of Iterator to be more meaningful
2. Add the missing PROXY_REFERER into header info
3. Add back the contentType statements for security reason.
TheMushrr00m/resource-proxy,Ricardh522/resource-proxy,jontwo/resource-proxy,bsvensson/resource-proxy,guo7711/resource-proxy,TheMushrr00m/resource-proxy,phpmaps/resource-proxy,phpmaps/resource-proxy,NoashX/resource-proxy,jontwo/resource-proxy,Ricardh522/resource-proxy,enjine/resource-proxy,Esri/resource-proxy,NoashX/resource-proxy,guo7711/resource-proxy,Esri/resource-proxy,bsvensson/resource-proxy