[WIP] start working on channels blacklisting

Opening this ticket for discussion : 

- Something I proposed would be to add css class to `div.stream.item` to each channel. I can find a stream name as `/div.stream.item > p > a[href]/.substr(1) // remove the slash before`.
  The problem here being that we need to tag the `div`s ourselves, because the CSS4 syntax `div.stream.item < p < a` won't work : when, where ?.
  **Note** : the layout does work fine with just a `display: none`

- Hook something somewhere when new channels are pulled to remove those we don't want. How, where ?

- Another idea ?