WIP Add warning for mobile users attempting coding tutorials

[terichadbourne]

Closes #147 by warning users with low res devices that they won't be able to complete coding challenges without a keyboard.

Currently this catches you on any lesson page within a tutorial (excluding landing page and resources) that contains coding challenges, even if the current lesson happens to be a quick text-based intro to upcoming content. Propose changing so the modal only appears on the coding lessons themselves and adding a separate non-modal banner to the landing page and any preliminary non-coding lessons so you know to expect the negative experience before getting started but can still see the page.

[terichadbourne]

Working on a banner to use on the landing page of coding tutorials and on the non-coding lessons that are sometimes included in coding tutorials. How do you feel about this concept, @zebateira? If we included messaging about both the JavaScript and the device, we could use it across the board on these to also help warn folks who don't know how to code. We could also cut up the text conditionally so that it only mentions the device if our media query suggests your device won't work.

on landing page of coding tutorial

on non-coding lesson w/in coding tutorial

[zebateira]

Looking good 👍

Some concerns:

• Will it look too cramped when the a tutorial message shows up for new / updated tutorials? Would like to see that.
• Maybe it makes more sense to move the warning above the lesson title in the second case?