There are new dependencies on `importlib_metadata` (for Python < 3.8) and `packaging`, in order to avoid a self-import in `setup.py`. People proxying Loggerhead through Apache should install the `loggerhead[proxied]` extra; people running it via FastCGI, SCGI, or AJP should install the `loggerhead[flup]` extra.
The version handling rearrangements make it possible to install Loggerhead using `pip`.