choke message from peer is not handled

[kilork]

unhandled message from peer: Choke

http://www.bittorrent.org/beps/bep_0003.html

Connections contain two bits of state on either end: choked or not, and interested or not. Choking is a notification that no data will be sent until unchoking happens. The reasoning and common techniques behind choking are explained later in this document.

Data transfer takes place whenever one side is interested and the other side is not choking. Interest state must be kept up to date at all times - whenever a downloader doesn't have something they currently would ask a peer for in unchoked, they must express lack of interest, despite being choked. Implementing this properly is tricky, but makes it possible for downloaders to know which peers will start downloading immediately if unchoked.

choke and not interested logic is completely missing currently. Even it works somehow, a spirit of protocol is not preserved.

We must support and cover this with test cases.