Add a .gitignore file. (#164)
Add a .gitignore file. (#164)

The file contents were taken from:

https://github.com/github/gitignore/blob/master/Python.gitignore
calberti/models,wangyang59/tf_models,jazcollins/models,xcyan/models,tombstone/models,jch1/models,jch1/models,tombstone/models,alexgorban/models,bousmalis/models,renjinghai/models,hang-qi/models,cshallue/models,xcyan/models,jiaphuan/models,sshleifer/object_detection_kitti,jazcollins/models,derekjchow/models,beomyeol/models,jiaphuan/models,sshleifer/object_detection_kitti,clinc/models,hang-qi/models,jazcollins/models,beomyeol/models,bousmalis/models,renjinghai/models,nathansilberman/models,xcyan/models,cshallue/models,jch1/models,hang-qi/models,wangyang59/tf_models,calberti/models,alexgorban/models,cshallue/models,cshallue/models,sshleifer/object_detection_kitti,r888888888/models,wangyang59/tf_models,bousmalis/models,jch1/models,jiaphuan/models,derekjchow/models,jazcollins/models,tombstone/models,derekjchow/models,zbigniewwojna/text-rcnn,sshleifer/object_detection_kitti,hang-qi/models,wangyang59/tf_models,hang-qi/models,clinc/models,wangyang59/tf_models,jiaphuan/models,clinc/models,jch1/models,bousmalis/models,jch1/models,wangyang59/tf_models,r888888888/models,calberti/models,hang-qi/models,sshleifer/object_detection_kitti,bousmalis/models,tombstone/models,r888888888/models,renjinghai/models,tombstone/models,r888888888/models,nathansilberman/models,xcyan/models,alexgorban/models,cshallue/models,jiaphuan/models,jazcollins/models,alexgorban/models,xcyan/models,r888888888/models,beomyeol/models,nathansilberman/models,alexgorban/models,xcyan/models,tombstone/models,jiaphuan/models,derekjchow/models,r888888888/models,jazcollins/models,derekjchow/models,bousmalis/models,sshleifer/object_detection_kitti