Only keep project specific prefs in ignore file

As per best practice ... .gitignore file will be a lot more elegant if it only lists files that are related to the projects. Global ignore file should keep overall ignores (OS files) & personal prefs like your personal editor generated files

- https://help.github.com/articles/ignoring-files
- http://augustl.com/blog/2009/global_gitignores/

Ps: Sorry for this ... I'm the one who committed these changes to the gitignore file before I'd set up a global_ignore. Didn't know better then.