Introduce ThumbnailDimensions model to simply Image.
Merge pull request #2589 from awagener/add_thumbnail_dimensions_model

Introduce ThumbnailDimensions model to simplify Image.
Add onOpenDialog and onCloseDialog javascript to admin.js
Merge pull request #2593 from ghoppe/add-dialog-js

Add onOpenDialog and onCloseDialog javascript to admin.js
Merge branch 'master' of github.com:refinery/refinerycms