Ajax selects for dashboard's product fields

This should greatly increase usability of the dashboard product update
page when managing a large amount of products.

Fixes #618

Conflicts:
	oscar/apps/dashboard/catalogue/forms.py
	oscar/apps/dashboard/catalogue/views.py
	oscar/static/oscar/js/oscar/dashboard.js
	oscar/views/generic.py

Widgets for product selection using select2 and ajax
Add default locale for currency

Babel tried to guess it from the LANG environment variable. But that's
not set in all environments, and would lead to an error in those cases.

Fixes #837
Allow easier customization of partners dashboard

This adds some blocks in the template and extracts the business logic part
of the partner user link view so that custom installations can modify this
behaviour with minimal code and template duplication.

Fixes #971
Show error messages on the ImageField itself.

This is relevant when you want to require an image for the product by
passing empty_permitted=False to the ProductImageForm.

Fixes #981
Apply the timepicker to dashboard's time fields.

We currently don't have any time fields in Oscar's stock dashboard.
But this change facilitates customising them if added, and makes good
sense as we already support datetime and date fields.
Add python-dev dependency to puppet manifest

@timjacobi reported it as missing but necessary.
context_object_name to IndexView needed for custom User models

The template is expecting 'user_list' so if using a custom user
model the name of the context variable changes. Explicitly setting it
prevents that.
Fix two typos

Fixes #983
AJAX product selects for dashboard promotions app

Those views also get rather slow if the product database is large. The
new AJAX select should fix it.
Fix for empty line in AJAX product selects

Previously, every load of new products would add a ------- entry to the
product list. Now it's only added for the first load, and when selecting
no product is actually an allowed choice.
Upgrade to Font Awesome 3.2.1

It's the latest version compatable with IE7. Still an upgrade from what Oscar used before.
FED fix for product update column stacking issue
Docs: Correct module names for core shipping methods
Drop docs for unsupported OSCAR_ALLOW_ANON_REVIEWS setting

This setting never did anything. Added documentation for it being
dropped.
Extend docs for permission-based dashboard

Done as it became apparent in #968 that further clarification is needed.
Fix docs warnings

Two links needed to be corrected.
Add blocks to make template customization easier