add vendoring with go dep

vendor/github.com/influxdata/influxdb/services/graphite/errors.go

@@ -0,0 +1,14 @@
+package graphite
+
+import "fmt"
+
+// An UnsupportedValueError is returned when a parsed value is not
+// supported.
+type UnsupportedValueError struct {
+	Field string
+	Value float64
+}
+
+func (err *UnsupportedValueError) Error() string {
+	return fmt.Sprintf(`field "%s" value: "%v" is unsupported`, err.Field, err.Value)
+}