Add meta-runtime deps automatically

[Slavek Kabrda]

I'm starting to think that meta-runtime deps for runtime (already implemented) and buildtime (requested in #13) should be added automatically. It is safe to add them and it's very convenient. I believe that there should be switches to disable these, instead of switches to enable.

[Iryna Shcherbina]

The spec2scl repository was moved to GitHub: https://github.com/sclorg/spec2scl

This issue was fixed by Pull Request #21. For more information please see the Issue on GitHub.