Support loading jars from local `./lib` dir

[johntyree]

Description:

pdfbox and its deps aren't available upstream anymore, but we include them directly in the ./lib dir, presumably so that people can copy them into ~/.m2 themselves and get things working. This makes onboarding extremely confusing for losers like myself that don't know anything about clojure or leiningen or are jvm novices in general.

This changes teaches lein to use ./lib as a local repo and use the jars it finds there, ignoring any checksum related issues since we don't have checksums for these and it's very unlikely that they get corrupted while being copied locally anyway.

Related issue (if applicable): fixes #539

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)

[codeGlaze]

Thoughts on why the linter is having a heart attack on this?

[johntyree]

@codeGlaze see #584. Looks like it was probably broken for awhile? At least as long as the pdfbox dep was unresolved.

[codeGlaze]

Merging this to create a chain for reverting if necessary, as mentioned on discord.