added a locked user to the user factories
Add hook for adding a link to another format to issues/index view

This will be used e.g. for an XLS export plugin.
Merge pull request #345 from jonasheinrich/feature/MeetingPluginIssue1565

added a locked user to the user factories
Merge pull request #358 from opf/feature/issue_export_hook

Add hook for adding a link to another format to issues/index view