inflate-upstream: support gzipped/deflated upstreams
inflate-upstream: support gzipped/deflated upstreams

Adds suport for silently inflating compressed upstreams. This is
good for when the link to the upstream is low bandwidth

This should fix https://github.com/pagespeed/ngx_pagespeed/issues/140

pagespeed/ngx_pagespeed,0x0mar/ngx_pagespeed,wanrui/ngx_pagespeed,digideskio/ngx_pagespeed,0x0mar/ngx_pagespeed,wanrui/ngx_pagespeed,pagespeed/ngx_pagespeed,digideskio/ngx_pagespeed