Merge branch 'easily-add-new-formset-to-product-update-page' into machtfit

* branch easily-add-new-formset-to-product-update-page:
  Provide a hook for cross-form validation
  Make it trivially easy to add more formsets to the product update page
  Unify __init__ method signature of formset classes
  customize FormSet class after calling inlineformset_factory
  Whitespace, Formatting, PEP8

https://github.com/tangentlabs/django-oscar/pull/1022
Merge branch 'origin/issue/1002/pbd_stockrecords' into machtfit

* branch origin/issue/1002/pbd_stockrecords:
  Pre-select partner if appropriate
  Pass user into StockRecordForm
  PBD: Enforce one stock record matching users partners

Force the partner to be the partner of the user when creating and editing stockrecords

Conflicts:
	oscar/apps/dashboard/catalogue/forms.py
	oscar/apps/dashboard/catalogue/views.py
Merge branch 'update-select2-to-3.4.5' into machtfit

* branch update-select2-to-3.4.5:
  Update select2 to version 3.4.5

https://github.com/tangentlabs/django-oscar/pull/1026
Merge branch 'origin/issue/856/productimages' into machtfit

* branch origin/issue/856/productimages:
  CSS fixes for product image handling
Merge branch 'contain-productimages-z-index' into machtfit

* branch contain-productimages-z-index:
  Create a new stacking context for the freakishly large z-index values used in upload-images

https://github.com/tangentlabs/django-oscar/pull/1030