Include pdf.js library.

[rosiel]

What does this Pull Request do?

Includes pdf.js in the starter site.

This will make the pdf.js library available [edited to say: as part of the starter-site]. Currently when you create an ISLE site that uses the Starter Site, pdf.js is not available. The Playbook does currently install pdf.js on its own, so a PR will follow to remove that.

• Related GitHub Issue: Reported by @nigelgbanks

• Other Relevant Links: (Google Groups discussion, related pull requests,
  Release pull requests, etc.)

What's new?

• List pdf.js as a package, similar to the install profile.

• Require it.

• Does this change add any new dependencies? yes, it adds one that was missing!

• Does this change require any other modifications to be made to the repository
  (i.e. Regeneration activity, etc.)? no

• Could this change impact execution of existing code? no

How should this be tested?

• If you have a starter site on ISLE before this PR, notice it doesn't include pdf.js
• Spin up a new starter site on ISLE with this PR. Create a PDF and see that it displays in the viewer.

Documentation Status

• Does this change existing behaviour that's currently documented? ** no**
• Does this change require new pages or sections of documentation? no
• Who does this need to be documented for? n/a
• Associated documentation pull request(s): ___ or documentation issue ___

Additional Notes:

Any additional information that you think would be helpful when reviewing this
PR.

Interested parties

Tag @nigelgbanks @adam-vessey

[nigelgbanks]

Tested it locally works a treat.