Allow the OS to select a free port for each test server. For

Allow the OS to select a free port for each test server. For
DebuggingServerTests, construct SMTP objects with a localhost argument
to avoid abysmally long FQDN lookups (not relevant to items under
test) on some machines that would cause the test to fail. Moved server
setup code in the server function inside the try block to avoid the
possibility of setup failure hanging the test.  Minor edits to conform
to PEP 8. [GSoC - Alan McIntyre]