GitLab

use a third-party pubsub library for internal communications

Insights:
* Within bitswap, the actors don't need anything more than simple pubsub
behavior. Wrapping and unwrapping messages proves unneccessary.

Changes:
* Simplifies the interface for both actors calling GetBlock and actors
receiving blocks on the network
* Leverages a well-tested third-party pubsub library

Design Goals:
* reduce complexity
* extract implementation details (wrapping and unwrapping data, etc)
from bitswap and let bitswap focus on composition of core algorithms
operations

procedure is to execute
```
cd my/github.com/jbenet/go-multiaddr
git pull
cd my/github.com/jbenet/go-ipfs
godep update github.com/jbenet/go-multiaddr
```

dependencies are vendored into Godeps/_workspace and commit versions are
recorded in Godeps.json

update datastore to e89f0511
update go.crypto