Remove legacy code and simplify stubbing

Splitting the class name to get the outer-most namespace/class appears
to be a throw-back to when sub-types (e.g. Speeches) were namespaced
below their parent class.
Tidy up TODO and whitespace

TODO is misleading - there are current no plans to change this test.
Merge pull request #558 from alphagov/searchable-take-part-pages

Searchable take part pages