appliance/postgresql: Use atomic.Value for config
appliance/postgresql: Use atomic.Value for config

This allows us to read the postgres config and online state
concurrently so that we can expose a status endpoint.

Signed-off-by: Jonathan Rudenberg <3692bfa45759a67d83aedf0045f6cb635a966abf@titanous.com>

tonicbupt/flynn,felixrieseberg/flynn,supermario/flynn,technosophos/flynn,kgrz/flynn,TribeMedia/flynn,technosophos/flynn,supermario/flynn,GrimDerp/flynn,supermario/flynn,flynn/flynn,GrimDerp/flynn,felixrieseberg/flynn,jzila/flynn,flynn/flynn,TribeMedia/flynn,GrimDerp/flynn,TribeMedia/flynn,clifff/flynn,schatt/flynn,justintung/flynn,kgrz/flynn,pkdevbox/flynn,philiplb/flynn,supermario/flynn,jzila/flynn,josephglanville/flynn,shads196770/flynn,kgrz/flynn,justintung/flynn,pkdevbox/flynn,tonicbupt/flynn,shads196770/flynn,lmars/flynn,schatt/flynn,GrimDerp/flynn,rikur/flynn,jzila/flynn,technosophos/flynn,Brandywine2161/flynn,benbjohnson/flynn,benbjohnson/flynn,pkdevbox/flynn,lmars/flynn,clifff/flynn,jzila/flynn,clifff/flynn,lmars/flynn,jzila/flynn,tonicbupt/flynn,technosophos/flynn,clifff/flynn,schatt/flynn,clifff/flynn,arekkas/flynn,felixrieseberg/flynn,Brandywine2161/flynn,tonicbupt/flynn,TribeMedia/flynn,lmars/flynn,ozum/flynn,Brandywine2161/flynn,josephglanville/flynn,schatt/flynn,ozum/flynn,ozum/flynn,TribeMedia/flynn,rikur/flynn,ozum/flynn,josephglanville/flynn,philiplb/flynn,arekkas/flynn,GrimDerp/flynn,schatt/flynn,technosophos/flynn,kgrz/flynn,rikur/flynn,justintung/flynn,josephglanville/flynn,philiplb/flynn,benbjohnson/flynn,josephglanville/flynn,flynn/flynn,whouses/flynn,justintung/flynn,philiplb/flynn,pkdevbox/flynn,whouses/flynn,Brandywine2161/flynn,shads196770/flynn,shads196770/flynn,Brandywine2161/flynn,whouses/flynn,flynn/flynn,clifff/flynn,josephglanville/flynn,philiplb/flynn,shads196770/flynn,supermario/flynn,schatt/flynn,whouses/flynn,TribeMedia/flynn,arekkas/flynn,arekkas/flynn,pkdevbox/flynn,kgrz/flynn,benbjohnson/flynn,whouses/flynn,benbjohnson/flynn,flynn/flynn,ozum/flynn,benbjohnson/flynn,kgrz/flynn,lmars/flynn,jzila/flynn,Brandywine2161/flynn,tonicbupt/flynn,rikur/flynn,rikur/flynn,justintung/flynn,GrimDerp/flynn,arekkas/flynn,pkdevbox/flynn,felixrieseberg/flynn,supermario/flynn,ozum/flynn,felixrieseberg/flynn,whouses/flynn,justintung/flynn,shads196770/flynn,rikur/flynn