[ktest] simplification and refactoring

I finally made the changes that I had in mind for a while.

* Instead individually passing settings, `KTestOptions` object is passed between classes. This became a problem after we had more and more global settings.
* I removed string constants. Since they can't be used in annotations, most of them were left unused after moving to JCommander. For uniformity I removed the rest.
* Some various unused stuff removed.
* Injected `KExceptionManager` is used instead of the one from `GlobalSettings`.

Just to make sure I'll run test suite on Windows manually.
While I'm not 100% sure, I think this may be considered a SAX error and we can re-use the class. From [the documentation](http://docs.oracle.com/javase/7/docs/api/org/xml/sax/SAXException.html):

> This class can contain basic error or warning information from either the XML parser or the application: a parser writer or application writer can subclass it to provide additional functionality.

Do you know any better exception class to use here? All I need is to pass a message -- I can't provide any other information.