Removed history from ostia_monthly.nc
Merge pull request #7 from esc24/remove_iris_history

Removed history from ostia_monthly.nc
ENH: Added ORCA2 data

Duplicate ORCA2 data which has origins from the iris test data
repository.  Moved to here as it is to be used for a gallery example.
ENH: Reduced orca2 complexity
Merge pull request #9 from cpelley/orca2_dat

ENH: Added ORCA2 data