Adds an empty changelog file and a reminder to update it when opening
pull requests.
Also, adds a 1.0.0 version number in the package.json, which is what
we _could_ use for version numbering.
This version will count lines of code in each file serially. It still
runs all file system operations asynchronously. The only difference now
is that it will only count one file at a time. It is slower, but it
is able to count large repositories without running out of memory.