cleaned up xml loading in case of missing arguments
cleaned up xml loading in case of missing arguments

MorganDawe/islandora_internet_archive_bookreader,Islandora/islandora_bookreader,MorganDawe/islandora_internet_archive_bookreader,Islandora/islandora_bookreader,islandora-deprecated/islandora_bookreader,ppound/islandora_bookreader,ppound/islandora_bookreader,islandora-deprecated/islandora_bookreader,islandora-deprecated/islandora_bookreader,Islandora/islandora_bookreader