Add basic shipping method list view
A shipping method can now be created
A shipping method can now be edited
A shipping method can now be deleted
Add a method detail view (for band editing)
A weight band can now be deleted
Ensure weights and charges are positive

Based on http://stackoverflow.com/questions/12384460/allow-only-positive-decimal-numbers

Hmmm, Oscar has a PositiveInteger model field but I suspect we don't
really need it (or should refactor it to use validators).
Add meandering happy path smoke test

Not 100% sure if this is a good idea, but this commit adds a large
functional test that walks through most of the happy paths of the
shipping method dashboard. It's much simpler to write this journey in
one test method rather than separate test methods that require
progressively more set-up each time.
Minor template improvements

- Show method countries as a list
- Show number of bands on list page
- Show view button on list page
- Use WYSIWYG widget on description field
Add HTML flash messages
Ensure test assertion works in Django 1.5

Seems ValidationError got a rewrite for 1.6.
Use "kg" instead of "Kg"
Use alternative title markup in release doc
Disable the weight-based shipping dashboard by default

It will be confusing if the dashboard for weight-based shipping methods
is enabled but not the shipping methods themselves.
Add section on new dashboard in v0.8 release notes
Merge pull request #1360

Conflicts:
	oscar/apps/shipping/abstract_models.py