Adding fix for #281 with tests, needs review
Allowing ExceptionsVerifier to be properly chained
Adding a whereTopLevelExceptionContainsString() to TopLevelExceptionVerifier
Updating ServeCommandTest to use this new testMethod to assert the INVALID_PORT_MESSAGE was output to the user
Merge pull request #299 from BladeRunnerJS/port-argument

allowing port to be passed in to serve command with -p flag, fixes #281