ListMultipart fixes (#1392)
ListMultipart fixes (#1392)

* ListMultipart: listLeafEntries() - return earlier if a directory is found.
* ListMultipart: do listLeafEntries() only for directories.
jimjag/minio,vadmeste/minio,jimjag/minio,dutchcoders/minio,dutchcoders/minio,abperiasamy/minio,abperiasamy/minio,krishnasrinivas/minio-daily,rajivm/minio,rushenn/minio,harshavardhana/minio,hackintoshrao/minio,krishnasrinivas/minio,harshavardhana/minio,rushenn/minio,hackintoshrao/minio,minio/minio,harshavardhana/minio,donatello/minio,dvstate/minio,harshavardhana/minio,aead/minio,abperiasamy/minio,aead/minio,krishnasrinivas/minio,donatello/minio,fwessels/minio,luomeiqin/minio,aead/minio,aead/minio,NitishT/minio,aead/minio,harshavardhana/minio,hackintoshrao/minio,jimjag/minio,harshavardhana/minio,fwessels/minio,jimjag/minio,minio/minio,krishnasrinivas/minio,NitishT/minio,brendanashworth/minio,brendanashworth/minio,rajivm/minio,brendanashworth/minio,fwessels/minio,hackintoshrao/minio,luomeiqin/minio,alexellis/minio,dutchcoders/minio,aead/minio,balamurugana/minio,aead/minio,vadmeste/minio,mkash32/minio,NitishT/minio,krisis/minio,mkash32/minio,luomeiqin/minio,harshavardhana/minio,abperiasamy/minio,krishnasrinivas/minio-daily,aead/minio,brendanashworth/minio,luomeiqin/minio,harshavardhana/minio,rushenn/minio,dvstate/minio,mf-00/newgo,koolhead17/minio,krisis/minio,fwessels/minio,balamurugana/minio,rushenn/minio,dvstate/minio,krishnasrinivas/minio,alexellis/minio,dvstate/minio,koolhead17/minio,NitishT/minio,dutchcoders/minio,mf-00/newgo