Some minor linting fixes and general style/scope changes, which should
have no impact on the overall application. Also moved to the offical
CircleCI UPX Orb, rather than my own (which is still maintained by me).
Making some improvements to the future maintainability of the project,
namely in the form of tests. Also implemented a new "dist" command to
the Makefile that packs up the binaries, and will eventually be expanded
to do more legwork when prepping for a release.
Updated file providers to use io.Reader over an explicit multipart file,
and removed the handler in favour of a plain filename, since that was
it's primary purpose.