Properly populate metadata with Zeiss ROIs

`filterMetadataPass7` was trying to use data not yet noted by `storeROIs`. After this fix, the images should be properly linked to their ROIs.

Discovered in investigating http://trac.openmicroscopy.org.uk/ome/ticket/10097

In testing, take a look at `data_repo/test_images_roi/zvi/` and see if via OMERO.web you can see ROIs in images.