wdaike/ngx_upstream_jdomain#7

[nicholaschiasson]

Clone of wdaike/ngx_upstream_jdomain#7.

I expect this could be a rather large change, as it represents changing the underlying way the module caches resolved IP addresses so that they are provided to the upstream via server. I think in doing this, it opens the door to a bigger change to expose the features exposed by the server directive through the jdomain directive. This could potentially be an entire design (breaking) change of the jdomain directive to effectively wrap the server directive, allowing jdomain to support all the same attributes server has, with the added functionality jdomain offers.