markdown links don't render in tip boxes

[Michael Zingale]

In the 0-Preliminaries notebook, the link to installing Jupyter in this box:

<div class="alert alert-info">
**Exercise:** Ensure that you have Jupyter installed on your computer. [Click here](http://jupyter.org/install) for installation information.
</div>

does not render as a link. This is likely the same for all other markdown in boxes.

[Christopher Thomas DeGroot]

This is related to the following: https://github.com/jupyter/notebook/issues/4504. The fix is known so I’ll go through and implement it.