adding git ignore file
adding git ignore file

Copied from
https://github.com/github/gitignore/blob/master/Python.gitignore

sjsrey/pysal,ljwolf/pysal_core,TaylorOshan/pysal,chhao91/pysal,TaylorOshan/pysal,lixun910/pysal,sjsrey/pysal_core,nathania/pysal,jlaura/pysal,darribas/pysal,lixun910/pysal,ljwolf/pysal,sjsrey/pysal_core,ljwolf/pysal_core,hasecbinusr/pysal,schmidtc/pysal,pastephens/pysal,spreg-git/pysal,weikang9009/pysal,darribas/pysal,badjr/pysal,pedrovma/pysal,pastephens/pysal,hasecbinusr/pysal,chhao91/pysal,jlaura/pysal,jlaura/pysal,pastephens/pysal,badjr/pysal,sjsrey/pysal_core,spreg-git/pysal,dfolch/pysal,ljwolf/pysal_core,lanselin/pysal,schmidtc/pysal,ljwolf/pysal,nathania/pysal,TaylorOshan/pysal,hasecbinusr/pysal,lixun910/pysal,ljwolf/pysal,dfolch/pysal,pysal/pysal