Add Generic Controller Related Metrics

To enhance operatability for the service using norman framework,
It's better to expose internal state as detail as possible.
This is the just starting point but at least which handler is executed
often and which handler with which key's execution is often failed
metrics is very useful to spot the place operator have to dig in when
something happened.
So this commit added 2 metrics.
1: handler execution total count
2: handler execution failure total count

vendor/github.com/prometheus/procfs/doc.go

@@ -0,0 +1,45 @@
+// Copyright 2014 Prometheus Team
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package procfs provides functions to retrieve system, kernel and process
+// metrics from the pseudo-filesystem proc.
+//
+// Example:
+//
+//    package main
+//
+//    import (
+//    	"fmt"
+//    	"log"
+//
+//    	"github.com/prometheus/procfs"
+//    )
+//
+//    func main() {
+//    	p, err := procfs.Self()
+//    	if err != nil {
+//    		log.Fatalf("could not get process: %s", err)
+//    	}
+//
+//    	stat, err := p.NewStat()
+//    	if err != nil {
+//    		log.Fatalf("could not get process stat: %s", err)
+//    	}
+//
+//    	fmt.Printf("command:  %s\n", stat.Comm)
+//    	fmt.Printf("cpu time: %fs\n", stat.CPUTime())
+//    	fmt.Printf("vsize:    %dB\n", stat.VirtualMemory())
+//    	fmt.Printf("rss:      %dB\n", stat.ResidentMemory())
+//    }
+//
+package procfs