Failed connection is not closed

Step to reproduce

1. Run the client gui
2. At the plateform step, enter localhost as an adress (instead of localhost:9000)

Result

The gui handle the issue just fine, but gRPC keeps failing in the background

2016/04/14 17:58:13 grpc: Conn.resetTransport failed to create client transport: connection error: 
desc = "transport: dial tcp: missing port in address localhost";
Reconnecting to "localhost"...

Fix

Properly kill the client when connection fail.