Export plugin for Sherpa\romeo

Basing at information about differences (Sword protocol errors due to export to SHERPA/ROMEO) beetween SWORD protocol and SHERPA\ROMEO api, maybe it will be cool to create plugin for sherpa export

full doc for sherpa is here: http://www.sherpa.ac.uk/romeo/SHERPA%20RoMEO%20API%20V-2-9%202013-11-25.pdf

also some information is here: sherpa.ac.uk/romeo/apimanual.php