GitLab

This makes reading the docs much easier as it's clear what's "private" and
what's not.

fixes #238

This commit extends the bitswap protocol with two additional wantlist properties:

* WANT_HAVE/HAVE: Instead of asking for a block, a node can specify that they
  want to know if any peers "have" the block.
* WANT_HAVE_NOT/HAVE_NOT: Instead of waiting for a timeout, a node can explicitly
  request to be told immediately if their peers don't currently have the given
  block.

Additionally, nodes now tell their peers how much data they have queued to send
them when sending messages. This allows peers to better distribute requests,
keeping all peers busy but not overloaded.

Changes in this PR are described in: https://github.com/ipfs/go-bitswap/issues/186

When fetching optimized peers from the peer manager, return an optimization rating, and pass on to
request splitter

BREAKING CHANGE: interface change to GetOptimizedPeers and SplitRequests public package methods

Add comments to all exported functions, extract the utils for creating instances in testnet.go,
moves integration tests to bitswap_test

BREAKING CHANGE: removed one constant -- rebroadcastDelay -- which I believe was unused

Seperate want list into differentiated types - session tracking and regular

fix #13

Limits connection bandwidth in real world benchmarks so that blocks are delayed if single peer is
overused

fix #40

Add a unit test for session package

per https://github.com/golang/go/wiki/CodeReviewComments#comment-sentences