Episodes need teaching and exercise metadata set

[brendam]

make lesson-check is giving errors on the episodes because during development they have been set to ?? instead of int minutes. Once episodes are ready we need to replace these with estimates of teaching time for each episode.

[brendam]

Also decide what to set training to. Currently have

# training: http://swcarpentry.github.io/instructor-training
training: do-we-have-a-repo-of-python-training-resources ?

[c-martinez]

I set the training times to ?? because I was not sure how long they will take (guessing times will differ slightly from the original lessons). I would like to set the times once someone has taken them for a test drive (any volunteers?). We could set the times to 0 for now, to make the make lesson-check work?

[brendam]

I'm happy to wait until we get some estimates for the times - just raised an issue to make sure we remembered to fix it.