Syncing send/receive when piping

[franciscocpg]

This PR is about syncing send/receive when one is piping wsd.
Before this PR the command

echo 'a 
b   
c                                    
d                                    
e                                    
f' \
| wsd -url="wss://echo.websocket.org"

results

> a
> b
> c
> d
> e
> f
< a
< c
< c
< d
< f
< f

So messages are being sending asynchronously.

After this PR the results are these

> a
< a
> b
< b
> c
< c
> d
< d
> e
< e
> f
< f

Now messages are being sending synchronously (waiting for response before move on).