Use image.loadOriginalMetadata()

The Blitz Gateawy image.loadOriginalMetadata() method had a bug when this script was being developed, so a local copy of the method was used (with the fix). However, this issue has been fixed a long time now, AND the implementation of that method is changed in OMERO 5.x since the data is no longer retrieved from a file.

So, for this script to work on OMERO 5 (and 4.4) we should use image.loadOriginalMetadata().

Another issue I noticed, running this against an LSM file in 'develop' (OMERO 5.) is that the key-value pair for colour data is ``` "DataChannel Color #2": 16711680 ``` which was not recognised by the script. I made some changes to work with this data. It should still work with OMERO 4.4 data, but haven't checked.