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/fs_test.go

@@ -0,0 +1,13 @@
+package procfs
+
+import "testing"
+
+func TestNewFS(t *testing.T) {
+	if _, err := NewFS("foobar"); err == nil {
+		t.Error("want NewFS to fail for non-existing mount point")
+	}
+
+	if _, err := NewFS("procfs.go"); err == nil {
+		t.Error("want NewFS to fail if mount point is not a directory")
+	}
+}