Add the very basic EntLib Logging support.

Was adding a couple more test to have some coverage over the LogLevel -> TraceEventType mapping and they were failing. So even though we're swapping out the container here, the LogWriter instance is only fetched from the ServiceLocatorStub *once*. First test passes, subsequent ones fail because we're asserting on a new instance of write, but EntLib Log is using/caching the writer instance from the first test. Now I have state shared between tests. EntLib is a crock o'shite.