TODO:
* need unique slugs for errors so they don't overwrite each other on export.
- try to preserve origin slug. If not possible, generate random one.
* figure out what metadata to strip. e.g.
({'data': '<problem><p><h1>Finger Exercise 1...'},
{'data': '<problem points="1" type="lecture"><p><h1>Finger Exercise 1...'},
False)
- where did points and type come from? Do we want them there?
* separate broken and non-broken test courses
