Implemented search on queryset
Minor optimisation in ElasticSearchQuery
Allow query_string to be set to None
This allows match_all queries to be created
Changed default values of filters and prefetch_related to None
Fixed typo
Moved wagtailsearch test models into wagtail.tests models
Split up backend tests
Added more tests for ElasticSearch backend
Added tests for indexed class
Make sure field filters are sorted before checking them
Fixed python 3.2 incompatible migration
Moved search method into base search backend
Added search method to PageQuerySet
Implemented __in lookup in ElasticSearch backend

Also added an error message if a user attempts to use a subquery with the __in lookup.
Added get_indexed_objects method to Indexed class
This gives developers control over the QuerySet used when the model is added to the indexed
Use get_indexed_objects to speed up indexing of Images/Documents
Previously, this created a query for every single image and document to get the tags. This was very slow on RCA which has over 15000 images.
This commit fixes this by adding a prefetch_related to the QuerySet used for indexing.
Added some more FilterFields to Page
Use a multi_match query instead of a query_string query
Minor optimisation when building single field queries
Merge branch 'searchchanges/searchonqueryset' of https://github.com/kaedroho/wagtail into kaedroho-searchchanges/searchonqueryset