Bugfixes and minor improvements

• Enhancement: don't restrict to a role when presenting user selector widget
• Enhancement: always preserve authors in order, allow drag-and-drop reordering
• Enhancement: add dates of last refusal and acceptance of reviewing in peer selector widget
• New: onetime_multiple configuration option
• New: accept_reminder_interval configuration option
• Minor: add missing use_ssl configuration example
• Bugfix: didn't send e-mail review_declined when done automatically in cron job
• Bugfix: logging review changes missed article ID
• Bugfix: PO files were missing text for label_review_created
• Bugfix: regression from new copyright agreement code
• Bugfix: new peers sometimes didn't get peer ACL role
• Bugfix: editor-authors could still see peer activity in article history