server/server.go: make successful garbage collection log at info level
server/server.go: make successful garbage collection log at info level

chub/coreos-dex,coreos/dex,circleci/dex,chub/coreos-dex,rithujohn191/dex,ericchiang/dex,chub/coreos-dex,ericchiang/dex,rithujohn191/dex,circleci/dex,wolfeidau/dex,circleci/dex,ericchiang/dex,Calpicow/dex,coreos/dex,rithujohn191/dex,wolfeidau/dex,coreos/dex,Calpicow/dex,Calpicow/dex,wolfeidau/dex