File system rewrite

Today I decided to put my file system and markdown rendering functions in the infrastructure layer; my thinking was to push these low-level concerns as far down as possible and avoid having the handler or services do file system things at all costs.

Got the file system functions working nicely with tests, and wrote the service to use a filesystem interface satisfied by these functions.

Focusing on Terms handler, there is a lot left still, but I left for home on a good note: showFiles will actually display the files. All of the URLs on that page are currently empty, probably due to not being registered (so far I have only registered the showFiles route handler).