Do not send envVars in ServerInfo() (#4422)

Sending envVars along with access and secret
exposes the entire minio server's sensitive
information. This will be an unexpected
situation for all users.

If at all we need to look for things like if
credentials are set through env, we should
only have access to only this information
not the entire set of system envs.

cmd/web-handlers_test.go

@@ -236,6 +236,10 @@ func testServerInfoWebHandler(obj ObjectLayer, instanceType string, t TestErrHan
 	if serverInfoReply.MinioVersion != Version {
 		t.Fatalf("Cannot get minio version from server info handler")
 	}
+	globalInfo := getGlobalInfo()
+	if !reflect.DeepEqual(serverInfoReply.MinioGlobalInfo, globalInfo) {
+		t.Fatalf("Global info did not match got %#v, expected %#v", serverInfoReply.MinioGlobalInfo, globalInfo)
+	}
 }
 
 // Wrapper for calling MakeBucket Web Handler