Remove unused code as reported by SimpleCov
Merge pull request #110 from alphagov/remove-unused-code

Remove unused code as reported by SimpleCov
Change notes for manual sections
Merge pull request #112 from alphagov/change-notes

Change notes for manual sections
Get rid of the simplest wiring instances

These are providing some intermediate indirection without adding much
value.
Remove unused wiring
Don't pass api_client into PanopticonRegisterer

The API client and the way it's constructed is a very stable part of the
codebase. As it's likely to change significantly less frequently than
the PanopticonRegisterer itself needs to change, it's fine to rely on
the concrete details inside the class.

The advantage of doing this is that it reduces indirection (it's simpler
to follow what's happening without dependencies being passed in) and it
removes some noise from the wiring file.
Remove url_maker from wiring

`UrlMaker`s only dependency is Plek, which is both easy to construct and
stable, so make it build that for itself.

Since `UrlMaker` is only used in one place and now doesn't need any
arguments to construct it, just build it directly in the
application_controller.