Fixed reference paths in unit test project
Refactored quite a lot in the dibspaymentcheckoutcontroller to enable unit testing. Extracted what I consider as separate blocks of functionality into separate classes and interfaces. Altered singleton implementation of site settings to be constructor injected. About to alter controller to be single call.
First attempt at unit testing the check out process - I chose to create
tests for the dibs controller.
For a variety of reasons, quite a lot of refactoring was needed. It was
impossible to mock out purchaseorder, so I had to extend the order service
to add mapping to a new layer of model objects. This could and should be
done by something like AutoMapper in the future.
I removed a lot of protected methods from the base checkout controller,
instead moving the methods into separate interfaces, favoring composition
over inheritance.
There is a lot of dependency injection "cheating" (getting the dependency
when needed instead of at runtime, sneaking in mutability and making
dependencies much harder to find). To cater for the unit testing these had
to be removed and passed as parameters or injected to the constructor.
This, in turn, exposed classes with too many dependencies/ a high level of
coupling (GenericPaymentController).
I removed IMarket from DTO (OrderViewModel) to be able to create the
model.
Xhtmlstring is a bother! The properties of its type need to be virtual to
be able to test anything related to it at all. The IFragmentParser stuff
really should be handled some other way.

All in all, few tests are added at this point, but the solution is at a
stage where it's beginning to be testable. As usual, when writing the
tests, interfaces pop up all over the place, exposing both hidden and
blatant coupling. IMO the changes are needed, for the the solution to be
maintainable, but someone should really have a good look at this before
merging. There's no reason to believe I haven't introduced any hidden (or
blatant) bugs.
Merge branch 'dev'
Fixed merge conflict
Conflicts:
	src/CommerceStarterKit.Web.UnitTests/CommerceStarterKit.Web.UnitTests.csproj