Move usage of testing::internal::CaptureStdout to Logger

[MarkOates]

Sticky note:

Guards, when tested with testing::internal::CaptureStdout using an ASSERT_ that fails, will not restore state, will leak, and eventually crash.

A couple points:

1. testing::internal::CaptureStdout should only be used within Logger, and classes that want to output log messages should use Logger and not std::cout or std::cerr.
2. If test are leaking, look into using death tests, to ensure that leaky state does not occur.

[the-dragons-studio]

When I have time I might create some pull requests to help with this issue by getting rid of some of the std::cerr uses and replacing them with Logger instances.