Switch to using fork of project repository instead of copying a template

[bielsnohr]

This PR implements the antecedent changes in the lesson to enable changes in #226 to work properly for learners. It should only be merged after that PR because it is based on top of that source branch. Closes #249 .

[anenadic]

Updated inflammation template repo with branches to use when reviewing this PR (that also needs to be synched with the original inflammation template repo): https://github.com/thomaskileyukaea/python-intermediate-inflammation

[bielsnohr]

Updated inflammation template repo with branches to use when reviewing this PR (that also needs to be synched with the original inflammation template repo): https://github.com/thomaskileyukaea/python-intermediate-inflammation

@anenadic we agreed in the maintainers sprint that it is probably actually best to create a complete new and distinct learner project repo to avoid problems with any forked versions of this course. @steve-crouch please correct me on that if I misinterpreted.

Once we create that new repository, we can update the links here to point to it.

[anenadic]

Merging this to a new branch on the base repo. The next is merging this to dev after a round of reviews and then to gh-pages.