Load Oscar applications dynamically

When you are overriding a single app, you are not required to override
Oscar application. Make the life a little bit easier.
Fix issue with calling get_shipping_method
Allow custom static files to be tested in Oscar's sandbox
Revert currency template filter rename

No need for the rename since 0.5.
Reapply 4aea545d

I accidentally dropped all changes from the previous commit in a borked
merge.  Reapplying here.
Merge branch 'master' into fix-processing
Use queryset.none() instead of EmptyQuerySet in basket.all_lines
Raise keyed validation error in address

This is so that the postcode validation error is rendered next to the
postcode form field.  It doesn't actually work in Django 1.5 but will
start working in Django 1.6.  It is backwards compatible.
Adjust how shipping methods are loaded for checkout

The loading of a shipping method instance in the session wrapper is
deprecated.  Better to only marshall session data there.
Add ignore file to keep static folder in source control
Extend range model to include slug field

This is required for sites that allow ranges to be browsed.

This change includes a datamigration to slugify existing range names.

Fixes #906
Merge pull request #904 from tangentlabs/issue/custom-user-model-error

Use better exception for AUTH_USER_MODEL
Fix postal code regexes

Two were missing parens.

Fixes #902
Merge pull request #903 from LUKKIEN/fix-processing

Add amount to EventHandler.validate_payment_event args
Fix issue with None being passed to report formatter
Remove unnecessary method from range model
Fix building of demo site

Still needs more attention but this fixes the problems when running
"make demo".
Clean CSS

- Remove unnecessary CSS
- Correct indentation
- Split into smaller files

Fixes #895
Rework the dashboard password reset form
Merge branch pull request #901