minor #14 use only valid sort directions (xabbuh)
minor #14 use only valid sort directions (xabbuh)

This PR was merged into the master branch.

Discussion
----------

use only valid sort directions

fixes #9

Commits
-------

12046fb use only valid sort directions

alexgt9/EasyAdminBundle,ogizanagi/EasyAdminBundle,kamilZ/EasyAdminBundle,npotier/EasyAdminBundle,thomasbeaujean/EasyAdminBundle,OskarStark/EasyAdminBundle,Seanmcn/EasyAdminBundle,peterkokot/EasyAdminBundle,kamilZ/EasyAdminBundle,alexgt9/EasyAdminBundle,datagit/EasyAdminBundle,yceruto/EasyAdminBundle,ogizanagi/EasyAdminBundle,thomasbeaujean/EasyAdminBundle,seydu/EasyAdminBundle,javiereguiluz/EasyAdminBundle,gabiudrescu/EasyAdminBundle,yceruto/EasyAdminBundle,javiereguiluz/EasyAdminBundle,datagit/EasyAdminBundle,alexgt9/EasyAdminBundle,ogizanagi/EasyAdminBundle,seydu/EasyAdminBundle,OskarStark/EasyAdminBundle,kamilZ/EasyAdminBundle,gabiudrescu/EasyAdminBundle,OskarStark/EasyAdminBundle,yceruto/EasyAdminBundle,ogizanagi/EasyAdminBundle,jverdeyen/EasyAdminBundle,gabiudrescu/EasyAdminBundle,helios-ag/EasyAdminBundle,seydu/EasyAdminBundle,npotier/EasyAdminBundle,thomasbeaujean/EasyAdminBundle,datagit/EasyAdminBundle