Wire up unused ShippingAddressUpdateView

It looks fine and has tests. Must've been forgotten!

Reported by Peter Brooks in
https://twitter.com/pbrooks_uk/status/473243588814733312
Template timings panel now supports Python 3

Version 0.6.0 supports Python 3, and I bumped it to 0.6.1 in 89598e3.

That means we can drop the special casing for it in the settings file.
PEP8 fixes

Zero complaints by ./lint.sh now.
Use contextual markers for translatables

Suggested by @mbertheau

Also, I promise to Read The Funtastic Manuals first than PR.

PEP8 fixes amended by @maikhoepfel.

Fixes #1357.

Conflicts:
	oscar/apps/address/abstract_models.py
Use parent method to support all behaviour overriding options
Merge pull request #1358 from machtfit/use-parent-method

Use parent method to support all behaviour overriding options
Workaround for Django bug with pggettext_lazy

pgettext_lazy currently trips in released versions of Django when it's
passed a byte string: https://code.djangoproject.com/ticket/22565

The recent commit d3ddfa5f79c2197d7614c77ee6b96399acbd3918 added a lot
of contextual markers using pgettext, so a few views tripped.

The workaround is easy enough; just ensure all strings passed to
pgettext_lazy are unicode strings.
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 SI convention for kg

Fixes #1362
Use checkboxes to select/de-select facets

Step 1 towards multi-faceting...