Add the md5-hashed user email to user objects for use with gravatar (#78)

pkg/utils/md5_string.go

@@ -0,0 +1,30 @@
+//   Vikunja is a todo-list application to facilitate your life.
+//   Copyright 2019 Vikunja and contributors. All rights reserved.
+//
+//   This program is free software: you can redistribute it and/or modify
+//   it under the terms of the GNU General Public License as published by
+//   the Free Software Foundation, either version 3 of the License, or
+//   (at your option) any later version.
+//
+//   This program is distributed in the hope that it will be useful,
+//   but WITHOUT ANY WARRANTY; without even the implied warranty of
+//   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+//   GNU General Public License for more details.
+//
+//   You should have received a copy of the GNU General Public License
+//   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+package utils
+
+import (
+	"crypto/md5"
+	"fmt"
+	"io"
+)
+
+// Md5String generates an md5 hash from a string
+func Md5String(in string) string {
+	h := md5.New()
+	io.WriteString(h, in)
+	return fmt.Sprintf("%x", h.Sum(nil))
+}