Upgrade a few front end services

[xmedr]

As noted in pr #1088 there were a few dependencies/services we're using that contributed to some html validation errors (and therefore accessibility issues. These could stand to be updated:

• Recaptcha
  There’s a couple errors having to do with required_score and required attributes on inputs that are recaptcha specific. This github thread shows that this was taken of semi-recently.

• Leaflet
  We also got errors about a role attribute on <img> tags with empty alts. This was resolved in an update a couple years ago.

• Datatables
  We’re using an older version that's raising an error about roles on tables. This has been addressed in newer versions.

• Mozilla pdf.js
  PDFs are structured a bit strangely and it affects screen reader performance. Instead of a paragraph being it's own div, one word or a whole phrase in the middle of a sentence will be a div. This may be resolved by looking into mozilla's pdf.js

[antidipyramid]

We'll pick this up once the accessibility updates are in.