Blocklist setting

![](http://f.cl.ly/items/2h3G1a2a372E002i352T/pct-blocklist.png)

this adds a blocklist setting to the "more settings" section.
there's quite a lot going on in this regard [over at peerflix](https://github.com/mafintosh/peerflix/search?q=blocklist&ref=cmdform&type=Issues) and i consider this feature rather important due to obvious reasons.

it's a work in progress and i'm not even sure i've put everything where it actually belongs.
first, naive tests appeared to show that this (my changes) lead to freezes of the app and (i think) memory leaks. but the blocklist is actually being loaded -- so far, so good.
so, please bear with me. any advice is greatly appreciated.

also, it should be possible to enter a real http url into that field. for now, it only works with a local, extracted plain text list.