chore(deps:go-multiaddr) update to b90678896b52c

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
```
Merge pull request #46 from jbenet/deps/go-multiaddr-b90678896b52c3e5a4c8176805c6facc3fe3eb82

chore(deps:go-multiaddr) update to b90678896b52c