Use message collection for reporting back to VSTest

[OsirisTerje]

See discussion at #92

[CharliePoole]

@cklutz If you are willing to take this issue on, I'll assign it to you. You said you don't have much time, but I notice you already have the code in your fork. We could copy it, but I think it will be better done if you do it yourself.

[edoua]

Will this also be ported to nunit3-vs-adapter?
Thanks

[CharliePoole]

@edoua This is already fixed in the NUnit 3 adapter.

@OsirisTerje Isn't this issue already done?