CLI refactor (#396)

* refactor cli to improve ux and enable easy incorporation of prepare as a subcommand

* switches to use click, which removes some boilerplate and gets us some improved ux for free

* changes the entry point for the cli

* changes the name of the browser option to --open and makes the default false

server/__main__.py

@@ -8,5 +8,5 @@ if __package__ is None:
     __package__ = PKG_PATH.name
 
 # Main thing
-from .app.app import main
-main()
+from .cli.cli import cli
+cli()