Update add_image to require application, group and item id
Updated service classes to use new image paths
Add uri basename to the json output
Created an image derivative class for all of the variant images
Added thumbnail creation for images
Return a 404 when an image is not found
Fixed vips command for travis, fixed load order for collection matchers
Debugging vipsthumbnail
Removed old api route, updated iipsrv conf to serve requests to /images
Made new ImageSet class to handle responsibility of determining derivative paths.  Simplified Image class to only be responsible for reading image dimensions and type
Skip the vipsthumbnail spec on travis
Don't use the name 'skip' for a tag since that causes spec to skip specs
Find all derivative images for a given image
Added coveralls
Increased coverage
Fixed the derivative_filepaths spec to not be dependent on order
Cache the bundler directory between travis builds
Merge pull request #2 from ndlib/image_derivatives

Added thumbnail generation, refactored api structure