Add size info to bucket list api (#122)

Using madmin.AccountUsageInfo since that api
includes size already.
Also includes integration with UI.

go.mod

@@ -17,8 +17,8 @@ require (
 	github.com/jessevdk/go-flags v1.4.0
 	github.com/json-iterator/go v1.1.9
 	github.com/minio/cli v1.22.0
-	github.com/minio/mc v0.0.0-20200515191050-09c31c4ab28c
-	github.com/minio/minio v0.0.0-20200501193630-d1c8e9f31ba0
+	github.com/minio/mc v0.0.0-20200515235434-3b479cf92ed6
+	github.com/minio/minio v0.0.0-20200516011754-9cac385aecdb
 	github.com/minio/minio-go/v6 v6.0.56-0.20200502013257-a81c8c13cc3f
 	github.com/pquerna/cachecontrol v0.0.0-20180517163645-1555304b9b35 // indirect
 	github.com/satori/go.uuid v1.2.0