Make the original_directory and annotation_directory a property

bob/bio/face/database/arface.py

bob/bio/face/database/banca.py

bob/bio/face/database/caspeal.py

bob/bio/face/database/frgc.py

bob/bio/face/database/gbu.py

bob/bio/face/database/ijba.py

bob/bio/face/database/lfw.py

bob/bio/face/database/mobio.py

bob/bio/face/database/msu_mfsd_mod.py

bob/bio/face/database/multipie.py

bob/bio/face/database/replay.py

bob/bio/face/database/replaymobile.py

bob/bio/face/database/scface.py

bob/bio/face/database/xm2vts.py

bob/bio/face/test/test_databases.py