Edit templates
Consolidate edit_base template
Create and update actions
Further consolidate read and edit templates
Remove unused imports
Showcase Show/read/get
Fix order of image_url in show schema
Remove unnecessary logic code
Reorder image upload w/r/t dataset create/update.

The uploader changes the data_dict so the file name is correct when the
package is saved, so this has to happen before the db commit.
Remove unneeded code from PackageController subclass
Remove dictization file
Showcase image tag in template