Merge pull request #145 from sbesson/histogram_image_format_fetch

HistogramRequestHandler: fetch the image.format in the pixels query

src/main/java/com/glencoesoftware/omero/ms/image/region/HistogramRequestHandler.java

@@ -267,6 +267,7 @@ protected Map<Long, Pixels> retrievePixDescription(
                     iQuery.findAllByQuery(
                         "select p from Pixels as p "
                         + "join fetch p.image as i "
+                        + "left outer join fetch i.format "
                         + "left outer join fetch i.details.externalInfo "
                         + "join fetch p.pixelsType "
                         + "join fetch p.channels as c "