Bump version on develop.
Added optional start parameter to real_search to allow for pagination of results
Added test for limited results real search
Added size checks to test for limited results real search
Merge branch 'feature/issue-874-allow-limiting-of-real_search-results' into develop
Set version to 0.5.4 for release
Merge branch 'develop' into release/0.5.x

Conflicts:
	docs/conf.py
	setup.py
	vumi/__init__.py
Merge tag 'vumi-0.5.4'