Bugfix: Always use current KSP version when resolving relationships

- CKAN.dll: LatestAvailable now requires a version number

This means we can never go looking up mods which may be the wrong version
for our install by accident. It may also fix some edge cases like #602
where we may show the wrong versions being available.

Most of the changes in this commit are to the test cases, which now require
the mandatory argument. :)

Tested that this closes #610 with our NEAR test example.

- Relationship resolver now uses KSP version in resolution.

`LatestAvailableWithProvides` now requires a mandatory KSP version, so we
don't accidentally do this again.

Fixes #610.