fix bountysource org

the 'owncloud-mail' org was deleted

README.md

@@ -6,7 +6,7 @@
 [![Code Coverage](https://scrutinizer-ci.com/g/owncloud/mail/badges/coverage.png?b=master)](https://scrutinizer-ci.com/g/owncloud/mail/?branch=master)
 [![PHP Dependency Status](https://www.versioneye.com/user/projects/54e50fadd1ec5734f400078a/badge.svg?style=flat)](https://www.versioneye.com/user/projects/54e50fadd1ec5734f400078a)
 [![JS Dependency Status](https://www.versioneye.com/user/projects/567bd06ba7c90e003500033f/badge.svg?style=flat)](https://www.versioneye.com/user/projects/567bd06ba7c90e003500033f)
-[![Bountysource](https://img.shields.io/bountysource/team/owncloud-mail/activity.svg)](https://www.bountysource.com/teams/owncloud/issues?tracker_ids=216487)
+[![Bountysource](https://img.shields.io/bountysource/team/owncloud/activity.svg)](https://www.bountysource.com/teams/owncloud/issues?tracker_ids=216487)
 
 **An email app for [ownCloud](https://owncloud.org) (minimum version 8.0 & PHP 5.4).**