refresh gitignore

Retroactively add a .gitignore and remove the files you forgot to ignore in the first place from your repo.

ht: http://stackoverflow.com/questions/1139762/ignore-files-that-have-already-been-committed-to-a-git-repository

basically it’s just:

git add .
git commit -m 'committing all my stuff'
git rm -r --cached .
git add .
git commit -m 'holy crow, my ignored files will be deleted now!'