DATAMONGO-777 - Upgraded to Mongo Java Driver 2.11.3.

Upgraded to latest mongo Java Driver release to benefit from new API introduced (required to fix DATAMONGO-534). Adapted test cases to API changes in DuplicateKey.
DATAMONGO-534 - GridFsTemplate supports queries with sorting.

Upgraded to Mongo Java Driver 2.11.3 to be able to forward the sorting options contained in a Query to eventually be able to return sorted results when querying for files.