url-encode unicode chars in source and target url

[snarfed]

sending a webmention with a unicode char in the source url failed recently, we think because it needs to be url-encoded. basically the same bug as aaronpk/Telegraph#16.

source: https://snarfed.org/2017-02-27_day-69-initial-editing-support-for-quill-100daysofindieweb-•-aaron-parecki
target: https://aaronparecki.com/2017/02/27/4/day-69-editing-in-quill

the webmention receiver (p3k) responded with HTTP 400 { "error": "invalid_request", "error_description": "source or target were invalid" }: https://telegraph.p3k.io/webmention/11UXLeTChJmz6hXsbk/details

[pfefferle]

The plugin send the correct data, so I think it's more a problem of Telegraph, or am I wrong?

ping @aaronpk

[aaronpk]

• is not a URL-safe character. The plugin should be URL-encoding the • for the source parameter.