#295 replace ImageIo with Imaging library in stadtbildutils
 #295 added dependency to commons-imaging

since the added dependency is only available as snapshot version, a
fork of the current snapshot was released in the cismet repository.
#295 removed obsolete paint method in stadtbildAggregationRenderer
fixed #295. fixed imports and jalopy
Merge branch 'bug/295-stadtbild-aggregation-renderer-vm-crash' into dev