Changing code to use py-dag as a package instead of the internal file about dagobah

[thieman]

We are requiring py-dag version 1.0.0 currently. I think the library is currently on 2.5.0.

My general philosophy would be not to upgrade unless there is a feature in the newer version we specifically need, did you have a use case in mind?

[cmishra]

I was actually referring to your frozen py-dag version (1.0.0) vs a 'dag.py' file within dagobah itself.

I realized quickly after submitting that though that the latest dagobah version does already rely on your py-dag repository (instead of the dag.py file). This isn't the same as the version available via pip install dagobah. Installing from source left #175, but I haven't run into any problems running dagobah and py-dag 1.0.0 functionality is now available.

By 'haven't run into any problems' I meant via usage as a python package. I'm not using dagobah as a web app.