add command to install beets and allow running without config

[tymbalodeon]

Is it possible to install beets and a default config with the Makefile? In any case, instructions should be added to the README for setting up beets. Since the default config will likely fail, the CLI should allow for running the help commands without crashing, and display a warning that the config is not set up properly.

[tymbalodeon]

Beets gets installed by installing the CLI, so only a default configuration need be provided.