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.
Don't use capitals for apps
Dynamically load dashboard apps

Couple dashboard apps weren't included in OSCAR_CORE_APPS and couldn't
be dynamically loaded. I added those missing apps.
Use kwargs in {% url ... %} template tags

Fixes #881
Update backwards compatibility notes for new apps
Merge pull request #905
Don't show wishlists that contain product in dropdown

Thanks to @timjacobi for the fix.
Add template blocks to checkout shipping address template

Fixes #922
Fix sphinx documentation errors

 - make sure all pages are linked from somewhere
 - prohibit double indexing of source code modules
 - remove old unused offers (we use GIT, no need to keep old files)
 - use local version of Oscar logo

Fixes #921