Merge pull request #26 from wamberg/feature/new_datamodel

Feature/new datamodel
boolean radio buttons renders properly for crispy forms
redefine is_public for CreateExhibitForm as well
inital pass re-working modals - delete and profile edit working, exhibit edit almost
ensure shared apps point to a PublisedExhibit
ensure properties are loaded properly
only display source information if a source exists
Create abstract base freemix.exhibit.models.DataTransaction to be used for asynchronous data transformation and augmentation. Create viewshare.apps.upload.models.UploadTransaction to handle transformations with Akara.