Update to OrientDB 2.2.8

[ruliana]

OrientDB changed some of REST responses to better error codes.

This commit updates the error code handling and create a couple of new exceptions to correctly handle them.

(unfortunately, a previous PR is going with this one. I can separate them, but let me know if it's really necessary :) )

[coveralls]

Changes Unknown when pulling a4ebd0756deb722d9e1d25ea4ce92757c72a3439 on VAGAScom:update_to_orientdb_2_2_8 into * on veny:master*.