Do not create intermediate folders

As asked before, and recently by axnfell, some users will prefer (at least in some cases) to not have an intermediate folder create, but a "replace, skip, rename" dialog if some files already exists.

Also asked via mail by Jan.

Asked on the trac: http://trac.kekaosx.com/ticket/31
Asked on the forum: http://forum.kekaosx.com/viewtopic.php?f=6&t=2111

To do notes:

- [x] Add behaviour to always create a root folder named like the archive (**fixed in v1.2.0**)
- [ ] Add behaviour to never create a root folder
- [ ] Add dropdown in Preferences to choose from "Always/Automatic/Never" create the root folder
- [x] Use this option in the context menu items (**fixed in v1.2.0**)