Testing - Check build dependencies and sequence for OutOfProcess tests

[govert]

From @eeaston:

Another gotchya I think I’m seeing is that when running the test using out of process mode, I need to do a project->build in visual studio, instead of just running the test and expecting it to do the build for me. If I don’t do this, then it uses the previous built binaries.

If this is tricky to fix we should at least document it in the Readme.

[Sergey-Vlasov]

When unit tests and add-in code are in separate projects:

1. Changing a unit test and running the test rebuilds unit tests automatically.
2. Changing the add-in and running the test doesn't rebuild add-in automatically by default.

To make sure the add-in always rebuilds, in Project dependencies, set unit tests project Depends on add-in project.