Added simple user auth

Fixes #14.

Change-Id: I748933214f43ac7298f1e93c14bb0ee881976d43

errors/errors.go

@@ -0,0 +1,30 @@
+package errors
+
+import (
+	"fmt"
+	"net/http"
+)
+
+type HTTP struct {
+	error
+	Message string
+	Code    int
+}
+
+func (e HTTP) Error() string {
+	return fmt.Sprintf("%d: %s", e.Code, e.Message)
+}
+
+func ToHTTP(err error) *HTTP {
+	if err == nil {
+		return nil
+	}
+	rerr := &HTTP{
+		Message: err.Error(),
+		Code:    http.StatusInternalServerError,
+	}
+	if e, ok := err.(HTTP); ok {
+		rerr.Code = e.Code
+	}
+	return rerr
+}