Details, userpage:  Preserve referers
Allow sponsors to location target collections at house priority.
Fix location targeting for sponsors.

Also return 403 responses for invalid location targets, rather than
setting location to None.
Allow all users to view a requested ad.

Previously this was only allowed for sponsors or the owner of the ad.
Don't fire pixels or fetch trackers on requested ads.
default_thing_wrapper: Don't set rowstyle_cls, it will get overwritten.

Builder also calls add_props, which completely overwrites the attribute.
Always enable the new campaign button when closing the campaign editor.
Collapse creative editor  when opening campaign editor.
Support collections on promoted/inventory page.
Allow updated UI on pages other than promoted/edit_promo.
Make PromoteLinkEdit inherit from PromoteLinkBase.

Add methods for getting form data to PromoLinkBase.
Remove dependency on fill_campaign_editor from sponsored.js methods.
Allow setting default targeting type for targeting_field.
Make min/max constraints in timing_field optional.
Update sponsored/inventory with new UI.
Update sponsored/report page with new UI.
Update sponsored/roadblock page with new UI.
Make PromoteLinkNew subclass of PromoteLinkBase.

Not needed at this point, but for consistency.