Set up CI for report generation.

[mkcor]

This is only a test, to trigger a Travis CI build and see if build artifacts land at: https://mkcor.github.io/case_studies_Py/

I haven't completed everything:

• Ultimately, use Travis CI with containers;
• apply the author/title patch to rosi_py.tex file.

/cc @bayesways @redSlug

[mkcor]

Oops, I meant to submit a pull request against my master branch first: mkcor#1
Please hold on.

[mkcor]

Yay! Fixes #4 :)

The PDF export is automatically updated and lives here: https://mkcor.github.io/case_studies_Py/rosi_py/rosi_py.pdf

We could make builds faster by using container-based infrasture (see also checklist in the main PR description) and improve the project organization (see #5 and the following). But, for now, it works!

I decided to use the gh-pages branch to publish outputs, but other options exist.

@bayesways Please review! Thanks.