Support density parameter in downloads api
 - add image_resolutions table to database
 - all migrated images are High resolution
Add migration so that images with retina and standard defs are set as high and medium density respectively
WIP
Finished WIP which was altering XML structure
Don't force transactions yet.. b/c they aren't being cleaned up properly
During database migration, be sure to properly find classic versions and replace filenames with hashes
Fixing up classic versions so images are now migrated:
 - a Fake page is put in place to build relationship version -page -page/image -image
Services no longer use RESTeasy exceptions for not found, which made the migration require RESTeasy jars
 - restuctured `ImageService` to be composed of `ImagePageRelationshipService`
RESTeasy jars are now provided scope
Database testing pattern is now defined
 -`ImageServiceTest` is now in place
Merge pull request #4 from CruGlobal/imagery

Imagery