added .DS_Store to .gitignore files, add .gitignore file to repos that didn't have one
added .DS_Store to .gitignore files, add .gitignore file to repos that didn't have one

phetsims/chipper,concord-consortium/chipper,phetsims/chipper,phetsims/chipper,concord-consortium/chipper,concord-consortium/chipper,concord-consortium/chipper