Provide a better description

[baptistemanson]

I suggest a better description for the project:

Ultron is a proxy for event emitters. Event listeners set up through Ultron are flagged. You can then ask Ultron to remove all flagged listeners at once, leaving the non-flagged event listeners intact.

It is useful for instance when developing a library and you want to easily clean up your library listeners without impacting the ones set up by other libs.

[lpinca]

Feel free to open a PR.