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
Merge branch 'searchchanges/searchonqueryset' of https://github.com/kaedroho/wagtail into kaedroho-searchchanges/searchonqueryset
Page.search should invoke backend.search with cls as a plain arg, not a 'model' kwarg
Merge branch 'kaedroho-searchchanges/searchonqueryset'