#1246 Implement happy eyeballs for all IP address candidates for s2s
Description of feature:
Attempt to connect to all possible IP addresses (maybe up to a limit :)) of a hostname at once and use the first connection which succeeds (on whatever level you want to define "success").
Prosody behaves really badly if the first candidate is not connectable and fails with a timeout (blackholed or internet routing mess). The s2s connection will fail consistently until the source of the timeout is fixed.