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
prefixed FileSystem locations with scriptcs_
changed command line to assume REPL when no command or script name is passed
- this is to allow running modules without having to specify -repl, e.g. scriptcs -m "migrate"
added migrate module