Create .gitignore

the gitignore file for .class and more
Merge branch 'master' of https://github.com/mu-scregan/Rockhopper
Merge branch 'master' of https://github.com/mu-scregan/Rockhopper
Merge branch 'master' of https://github.com/mu-scregan/Rockhopper
Merge branch 'master' of https://github.com/mu-scregan/Rockhopper
Merge branch 'master' of https://github.com/mu-scregan/Rockhopper