Changes to login. (For some reason the hash-compare worked on
my Mac but not on Linux; now it works on both and should be correct.)

Minor changes to layout.
Tracker can now read torrent files and facilitate basic
peering exchange.

Very naive: sends all known peers; does not track clients.
Uses a secret token signed w/ an HMAC to authenticate
a user to the `babou` tracker.

The HMAC ensures that the user belongs to the same cluster of babous.
(In the future when multi-node trackers are supported.)

babou now sends a uint16 in the compact peer list. Support
for the dictionary peer-list is pending.
Refactoring of tracker server and torrent library.

User#SelectSecret() now operates on a string and handles encoding.
(As the primary use-case involves receiving a string from torrent clients.)

Peer objects are now split-up into an [on-demand] bencodable peer and a peer w/ status information.

GetPeerList() is now slightly-less-naive. -- It will return up to 30 peers currently.
Merge branch 'develop/tracker-ann'