Implement field validation for Site.is_default_site; resolves #289
Allow multiple sites with the same hostname but different ports; resolves #290
Add routing test for when two sites have the same hostname but different ports
Update Site.objects.get_by_natural_key() to include port
Update Site.find_for_request to respect https
Change the way we lookup the request port
Modify tests to include ports differently, add tests for unrecognised ports
Add test that requests on unrecognised ports are routed to the expected site if no ambiguity
Refactor port/site tests into new test case and individual tests
Merge branch 'master' into site_model_adjustments

Conflicts:
	wagtail/wagtailcore/models.py
Merge pull request #371 from nimasmi/site_model_adjustments

Site model adjustments
Merge remote-tracking branch 'torchbox/master' into scheduled-publishing
Fixed migration conflict