certificates go to directory ./out/ by default
Merge pull request #24 from ZIMK/feature/output-subdir

Unfortunately, this discussion is stuck, so I just merge this one because of the following reasons:
- I already use this branch by default, because it is a more clean way to work
- This branch is perfectly usable despite the fact, that the output dir is named "out"
- The essential part of this tool is the easy generation of SSL keys and certificate requests, not certificates