ctx closer races #270
mux test race #270
fixed dht race #270
fixed race in multiconn
fix(race condition)

https://github.com/jbenet/go-ipfs/issues/270
fix(bitswap_test) race cond

https://github.com/jbenet/go-ipfs/issues/270#issuecomment-61826022
Merge pull request #273 from jbenet/fix-data-races

Fix data races in #270
fix(exchange) add context to DialPeer
fix(net) pass contexts to dial peer
add do
fix(net) use Do to respect the caller's context
fix(do) child listens on ctx too
fix(bitswap) don't 'go' local function calls
fix(bitswap) always cancel on return