Fix #1695

[ralsina]

This avoids the unicode/bytes error under python3, BUT it still keeps the ed2k URL url-encoded llike this

<p>Here is an <a class="reference external" href="ed2k://%7Cfile%7CAudioBook-OrsonWelles-WarOfTheWorlds,Original,Uncut.mp3%7C54878208%7CB7E6517C258F0062832629718E91FFBC%7C/">eD2k link</a></p>

I have no idea if those are valid or not. @chaghi can you check?

[chaghi]

@ralsina it works.

The URL encoding doesn't seem to be a problem, at least with Firefox 37 and aMule 2.3.1 on Linux. If you click the (encoded) link on the rendered page, you get prompted by Firefox to handle it with aMule, and aMule parses it all right and starts the download.