Resolve issues around building containers; missing dependencies.

[kapsterman]

Description:

Related issue (if applicable): fixes #549 and #539 Since Cognitect has ceased making datomic-free versions available, the current method of building the orcpub-datomic container is permanently broken. This is a workaround. I've included a fix for the PDFBox (539) problem as well.

Checklist:

• [X] The code change is tested and works locally.
• [X] I have commented my code, particularly in hard-to-understand areas
• [X] I have made corresponding changes to the documentation if necessary
• [X] There is no commented out code in this PR.
• [X] My changes generate no new warnings (check the console)

[kapsterman]

Given that, as 'zots pointed out, we have other (better) ways to build the orcpub-datomic container, and a better solution to the PDFBox problem exists, maybe it's best to close the pull request.