* federation (ap, salmon)
* media (rich media, media proxy)
* upload (uploader proxy)
Each "part" will stop fighting others ones -- a huge federation outbound
could before make the media proxy fail to checkout a connection in time.
splitted media and uploaded media for the good reason than an upload
pool will have all connections to the same host (the uploader upstream).
it also has a longer default retention period for connections.
by default, hackney only sent TLS server name indication if TLS was locked
to TLS 1.2.
since there are many instances out there not speaking TLS 1.2, it is not
acceptable to lock SNI to TLS 1.2.
closes#261
