Add unit tests for edit_handlers.py. Lint edit_handlers.py.
Merge branch 'master' into edit-handlers-unit-tests

Conflicts:
	wagtail/wagtailadmin/edit_handlers.py
Remove broken test
Update edit handlers unit tests

Add more tests. Clean up modified class properties after tests finish.
Replace assertRegexpMatches with assertIn.
Merge branch 'master' into edit-handlers-unit-tests
Fix Travis test failures
Split ESResults into ESResults and ESQuery
Renamed a couple of methods on ElasticSearchResults
Added __repr__ method to ElasticSearchQuery
Removed ability to use prefetch_related in search queries
This will be replaced by search on queryset
Made finding objects for search results the responsibility of do_search
Slicing ESResults now returns a new ESResults object
Previously, slicing an ESResults object made it run a query against ElasticSearch and return the results
This commit changes this by making slice return a new ESResults object with start and stop limits applied. To get results, you now have to iterate the ESResults object.
len(ESResults) now runs query and gets the length of the results. Added ESResults.count() which asks Elasticsearch for the count but doesn't run the query
Added __repr__ method to ElasticSearchResults
Implemented results caching on ElasticSearchResults
Reorganise unit tests to obviate the use of del
Changelog entry for #342
Put prefetch_related back
Put prefetch related back in database backend
Merge pull request #343 from kaedroho/searchchanges/elasticsearchresults-refactor

Search Changes 2 - Refactor ElasticSearchResults class