Add xoauth2 support

README.md

@@ -375,7 +375,9 @@ ImapConnection Functions
 
     * **password** - <_string_> - Password for plain-text authentication.
 
-    * **xoauth** - <_string_> - OAuth token for [OAuth authentication](https://sites.google.com/site/oauthgoog/Home/oauthimap) for servers that support it.
+    * **xoauth** - <_string_> - OAuth token for [OAuth authentication](https://sites.google.com/site/oauthgoog/Home/oauthimap) for servers that support it (See Andris Reinman's [xoauth.js](https://github.com/andris9/inbox/blob/master/lib/xoauth.js) module to help generate this string).
+
+    * **xoauth2** - <_string_> - OAuth2 token for [The SASL XOAUTH2 Mechanism](https://developers.google.com/google-apps/gmail/xoauth2_protocol#the_sasl_xoauth2_mechanism) for servers that support it (See Andris Reinman's [xoauth2](https://github.com/andris9/xoauth2) module to help generate this string).
 
     * **host** - <_string_> - Hostname or IP address of the IMAP server. **Default:** "localhost"
 
@@ -637,4 +639,4 @@ Several things not yet implemented in no particular order:
   * UNSELECT (via UNSELECT extension -- http://tools.ietf.org/html/rfc3691)
   * SORT (via SORT extension -- http://tools.ietf.org/html/rfc5256)
   * THREAD (via THREAD=ORDEREDSUBJECT and/or THREAD=REFERENCES extension(s) -- http://tools.ietf.org/html/rfc5256)
-  * ID (via ID extension -- http://tools.ietf.org/html/rfc2971) ?
+  * ID (via ID extension -- http://tools.ietf.org/html/rfc2971) ?

lib/imap.js

@@ -1198,6 +1198,9 @@ ImapConnection.prototype._login = function(cb) {
     if (this._serverSupports('AUTH=XOAUTH') && 'xoauth' in this._options) {
       this._send('AUTHENTICATE XOAUTH ' + utils.escape(this._options.xoauth),
                  fnReturn);
+    } else if (this._serverSupports('AUTH=XOAUTH2') && 'xoauth2' in this._options) {
+      this._send('AUTHENTICATE XOAUTH2 ' + utils.escape(this._options.xoauth2),
+                 fnReturn);
     } else if (this._options.username !== undefined
                && this._options.password !== undefined) {
       this._send('LOGIN "' + utils.escape(this._options.username) + '" "'