red: add AliasCommandTests.ExecuteMethod.ShouldNotThrowAnExceptionWhenAnUnknownCommandIsPassed
green: implement AliasCommandTests.ExecuteMethod.ShouldNotThrowAnExceptionWhenAnUnknownCommandIsPassed
refactor: AliasCommand and AliasCommandTests
Merge pull request #879 from adamralph/730

improved feedback for alias REPL command