Added logic to TestUniversal.py to exercise the python APIs:

o SBDebugger.GetCurrentTarget()
o SBTarget.GetProcess()
o SBProcess.GetAddressByteSize()

in order to make sure that, indeed, 64-bit, followed by 32-bit processes have
been launched.

Added invoke() method to TestBase to factor in the tracing logic in one place.
This method allows an object to call a method with no arg reflectively.

llvm-svn: 112102