Fixed Ping (minor)

Fixed a link in the README (and capitalization).

This fixes the broken pinging. (the issue was the cluster
level, it's bein set incorrectly (off by one))

Anyway, this works now:

    [peer: QmfQTbC3LxfpK5WoyHW2WgnAzo6d6GePuq2wHTsJNXM5PS] Sent message type: 'PING' [to = QmNXUeFrV9gxR4aqJddEsfhWZLSJrUsfpUSeRb3R7xvSp9]
    [QmfQTbC3LxfpK5WoyHW2WgnAzo6d6GePuq2wHTsJNXM5PS] ping QmNXUeFrV9gxR4aqJddEsfhWZLSJrUsfpUSeRb3R7xvSp9 end (err = %!s(<nil>))

cc @whyrusleeping

New net interface

failing due to nil pointer dereference

sending

true -> always send to peer

false -> use ledger-based strategy described in IPFS paper draft 3

fix(bitswap) pass go vet

fixes #97

https://github.com/jbenet/go-ipfs/issues/97

until construction is complete on the actual async method

reverts changes from ec50703395098f75946f0bad01816cc54ab18a58

https://github.com/jbenet/go-ipfs/commit/ec50703395098f75946f0bad01816cc54ab18a58

changing the bitswap interace breaks tests and makes things a bit
difficult going forward. I think I have a temporary solution to replace
the async method.

this commit partially reverts changes from:

ec50703395098f75946f0bad01816cc54ab18a58

https://github.com/jbenet/go-ipfs/commit/ec50703395098f75946f0bad01816cc54ab18a58

@jbenet

Handshake library has been modified to use Secure Pipe. This test
targets the old implementation.

TODO: write a new handshake test

@perfmode using non-async version as apparently there's
a bug in async. will look into it.

@perfmode boom

There are (so far) two sorts of addresses that peers care about:

- peer network addresses, local to listen, saved to bootstrap.
  `config.Identity.Address`

- peer RPC network address, local RPC tcp endpoint
  `config.RPCAddress`

@whyrusleeping @perfmode

In the future, let's have a (signed) list of bootstrap
nodes. Ideally just a list of ipfs multiaddrs (with node.ID)

for now, ipfs add output format:

    added <hash> <path>
    ...

(these commands will adhere to strict formats.)

let's keep this a turn-on for testing sort of thing.
(want the outputs of commands like `ipfs add` to be
usable as inputs to other programs/scripts).

maybe we should consider adding a --debug (not -d),
once we figure out adding flags that apply globally :)
@whyrusleeping

(perhaps should be logged instead)