Don't fallback to default apps when app is found

Fixes #923
Test that Oscar doesn't fallback
Add shipping tax property to order model
Fix date format in templates
Add helper property to address model for ISO code

It gets boring having to type iso_3166_1_a2 all the time...
Dropdown using select2 now have correct width

Source: http://stackoverflow.com/questions/12683907/set-the-width-of-select2-input-through-angular-ui-directive
Disable adding products to range if "Includes All Products" option is set.

Show a friendly message instead.
Ensure migrations reference appropriate user model

Fixes were required inthe basket, order, partner and wishlist apps.
Allow ranges to be be public
Change field name to is_public
Add customer-facing range detail view
Add description field to range
Cover range improvements in v0.6 release notes
Tweak to range template
Add FP Sport as new case study to README
Merge pull request #923 from tangentlabs/issue/923-dont-fallback

Don't fallback to default apps when ImportError is raised
Disable template timings panel by default
Add 'retail' price property to base price object
Update demo templates

Use strategy to look-up prices and availability
Comment out template timings from demo settings