Digitalocean provider (#171)

* Implement Digitalocean provider
* Vendor digitalocean lib
* Enable SRV for Digitalocean and fix the tests
* Test cname etc. records pointing to the same domain

vendor/github.com/digitalocean/godo/strings.go

@@ -0,0 +1,92 @@
+package godo
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"reflect"
+)
+
+var timestampType = reflect.TypeOf(Timestamp{})
+
+// Stringify attempts to create a string representation of DigitalOcean types
+func Stringify(message interface{}) string {
+	var buf bytes.Buffer
+	v := reflect.ValueOf(message)
+	stringifyValue(&buf, v)
+	return buf.String()
+}
+
+// stringifyValue was graciously cargoculted from the goprotubuf library
+func stringifyValue(w io.Writer, val reflect.Value) {
+	if val.Kind() == reflect.Ptr && val.IsNil() {
+		_, _ = w.Write([]byte("<nil>"))
+		return
+	}
+
+	v := reflect.Indirect(val)
+
+	switch v.Kind() {
+	case reflect.String:
+		fmt.Fprintf(w, `"%s"`, v)
+	case reflect.Slice:
+		stringifySlice(w, v)
+		return
+	case reflect.Struct:
+		stringifyStruct(w, v)
+	default:
+		if v.CanInterface() {
+			fmt.Fprint(w, v.Interface())
+		}
+	}
+}
+
+func stringifySlice(w io.Writer, v reflect.Value) {
+	_, _ = w.Write([]byte{'['})
+	for i := 0; i < v.Len(); i++ {
+		if i > 0 {
+			_, _ = w.Write([]byte{' '})
+		}
+
+		stringifyValue(w, v.Index(i))
+	}
+
+	_, _ = w.Write([]byte{']'})
+}
+
+func stringifyStruct(w io.Writer, v reflect.Value) {
+	if v.Type().Name() != "" {
+		_, _ = w.Write([]byte(v.Type().String()))
+	}
+
+	// special handling of Timestamp values
+	if v.Type() == timestampType {
+		fmt.Fprintf(w, "{%s}", v.Interface())
+		return
+	}
+
+	_, _ = w.Write([]byte{'{'})
+
+	var sep bool
+	for i := 0; i < v.NumField(); i++ {
+		fv := v.Field(i)
+		if fv.Kind() == reflect.Ptr && fv.IsNil() {
+			continue
+		}
+		if fv.Kind() == reflect.Slice && fv.IsNil() {
+			continue
+		}
+
+		if sep {
+			_, _ = w.Write([]byte(", "))
+		} else {
+			sep = true
+		}
+
+		_, _ = w.Write([]byte(v.Type().Field(i).Name))
+		_, _ = w.Write([]byte{':'})
+		stringifyValue(w, fv)
+	}
+
+	_, _ = w.Write([]byte{'}'})
+}