PLT-4357 adding performance monitoring (#4622)

* WIP

* WIP

* Adding metrics collection

* updating vendor packages

* Adding metrics to config

* Adding admin console page for perf monitoring

* Updating glide

* switching to tylerb/graceful

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

@@ -0,0 +1,31 @@
+package procfs
+
+import "testing"
+
+func TestNewLimits(t *testing.T) {
+	p, err := FS("fixtures").NewProc(26231)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	l, err := p.NewLimits()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	for _, test := range []struct {
+		name string
+		want int
+		have int
+	}{
+		{name: "cpu time", want: -1, have: l.CPUTime},
+		{name: "open files", want: 2048, have: l.OpenFiles},
+		{name: "msgqueue size", want: 819200, have: l.MsqqueueSize},
+		{name: "nice priority", want: 0, have: l.NicePriority},
+		{name: "address space", want: -1, have: l.AddressSpace},
+	} {
+		if test.want != test.have {
+			t.Errorf("want %s %d, have %d", test.name, test.want, test.have)
+		}
+	}
+}