Update ImageGalleryAlbum.php

ImageID should just be image as per a change in the GridFieldBulkEditingTools module. 

https://github.com/colymba/GridFieldBulkEditingTools/commit/6a105b9a96e37c4155b817cc0d8ad97299f47d4c
Merge pull request #3 from LiamW/patch-1

Update ImageGalleryAlbum.php