The shim tests use many go routines and cause the go-logging
infrastructure to be initialized many, many times. This introduces
races.

Avoid the races by making initialization run once and moving the logging
specific test to drive the underlying, unexported method.

Change-Id: I175d103b2965b0813baf588def35e3245b77b004
Signed-off-by: Matthew Sykes <sykesmat@us.ibm.com>