Release a beta of the Firefox WebExtensions port

Created by: Bisaloo

If I got it right, the webextension port is ready or close to be since you released a chromium version of decentraleyes.

I think you should release a beta before the official release of Firefox 57. HTTPS-Everywhere just did this and the firefox and chromium API are apparently different enough to cause some issues.

I believe many followers of this github repo would be happy to help you test it.