ERT 530: Locking on fs level with one common lock file
Included header
Added testing
ERT 530: Added logic for when fs level lock fails: read-only on block level must be set to true, thereby forcing dataowner on blcoklevel to false
ERT 530: Changes after review: Removed block_level_lock parameter from enkf_fs, set to constant false in block_fs_driver
ERT-530: Locate lock file in case directory
ERT-530: Changes to test due to moved lock file
ERT-530: Change in test
Merge pull request #420 from chflo/ERT_530_common_lock_file

Ert 530 common lock file