Added unit tests for models.Invite.add

no issue

- replaced token creation by `lib.common.security`
- added unit tests for adding invites
- allow a different invite status for internal access

ghost/security/lib/tokens.js

@@ -2,7 +2,25 @@
 
 const crypto = require('crypto');
 
-exports.resetToken = {
+module.exports.generateHash = function generateHash(options) {
+    options = options || {};
+
+    const hash = crypto.createHash('sha256'),
+        expires = options.expires,
+        email = options.email,
+        secret = options.secret;
+
+    let text = '';
+
+    hash.update(String(expires));
+    hash.update(email.toLocaleLowerCase());
+    hash.update(String(secret));
+
+    text += [expires, email, hash.digest('base64')].join('|');
+    return new Buffer(text).toString('base64');
+};
+
+module.exports.resetToken = {
     generateHash: function generateHash(options) {
         options = options || {};