Sys setup incremental tiny fixes

I was poking around on the research why the --no-interaction flag isn't working in the sys:setup:incremental command. But it is :-) So the error must be in my scripts which are calling n98-magerun.

During my ride through the source code of IncrementalCommand I made some fixes: Correct types of variables and removed unused variables. There is no change in the logic at all.

Thanks for merging