Auto merge of #287 - negator:patch-1, r=jdm
Auto merge of #287 - negator:patch-1, r=jdm

Update futures to 0.3

Using the `asynch` package with newer futures is failing to compile when trying to use the `futures.stream::StreamExt` module.

```
 | pub struct IpcStream<T>(UnboundedReceiver<OpaqueIpcMessage>, PhantomData<T>);
   | -----------------------------------------------------------------------------
   | |
   | doesn't satisfy `IpcStream<StorageThreadMsg>: futures::StreamExt`
   | doesn't satisfy `IpcStream<StorageThreadMsg>: futures::Stream`
   |
   = note: the following trait bounds were not satisfied:
           `IpcStream<StorageThreadMsg>: futures::Stream`
           which is required by `IpcStream<StorageThreadMsg>: futures::StreamExt`
   = help: items from traits can only be used if the trait is in scope
```

servo/ipc-channel