Added new search configuration format
Remove X-Requested-With header hacks on the incoming requests to preview_on_edit and preview_on_create - no longer necessary, because we're not passing that request to the preview logic

Conflicts:
	wagtail/wagtailadmin/views/pages.py
syntactic sugar for get_page_modes: change it to a property called preview_modes and add a default_preview_mode helper

Conflicts:
	wagtail/wagtailadmin/views/pages.py
rename display_modes to preview_modes for consistency

Conflicts:
	wagtail/wagtailadmin/views/pages.py
Deprecate the `show_as_mode` method in favour of `serve_preview` which additionally takes a 'request' argument
update view_draft and preview_for_moderation to call serve_preview (rather than serve, which for some page models might require additional args/kwargs)
output a DeprecationWarning if get_page_modes has been overridden
Merge pull request #419 from gasman/serve_preview

Use serve_preview() rather than serve() for all preview / moderation / view_draft actions
Added __repr__ to EditorsPicK
Make sure all editors picks are resaved on edit. Fixes #408

As we are setting the sort_order manually. The formset doesn't think the editors pick has changed so doesn't save it.
This caused a SQLite test to fail as NULL is always greater than any integer causing ordering to be incorrect.
Improved test_post_reorder test
Merge branch 'issue/408' of https://github.com/kaedroho/wagtail into kaedroho-issue/408
Merge branch 'kaedroho-issue/408'
fix documentation syntax errors / warnings
Merge pull request #344 from kaedroho/searchchanges/newsearchconfig

Search Changes 3 - New field configuration format
Merge branch 'master' into 146-display-calculated-usage

Conflicts:
	wagtail/wagtaildocs/models.py
	wagtail/wagtailimages/models.py