Self hosted mathjax

[ghost]

Closes #31

[ghost]

It works!, now, we might want a way to update mathjax with dependabot.

See #35

[zyachel]

that's sweet! I'll test it locally before merging.

[ghost]

that's sweet! I'll test it locally before merging.

Wait, I still need to do one thing more.

[ghost]

Please, check that everything works well. Make sure, if you have time, to check the hashes of the libraries I introduced, I could have potentially introduced a backdoor (obviously not) just as a security precaution.

[zyachel]

will do!