Updated generated client and server for Echo sample.

Examples/Echo/Generated/echo.client.pb.swift

@@ -24,6 +24,7 @@
 import Foundation
 import Dispatch
 import gRPC
+import SwiftProtobuf
 
 /// Type for errors thrown from generated client code.
 internal enum Echo_EchoClientError : Error {

Examples/Echo/Generated/echo.server.pb.swift

@@ -24,6 +24,7 @@
 import Foundation
 import Dispatch
 import gRPC
+import SwiftProtobuf
 
 /// Type for errors thrown from generated server code.
 internal enum Echo_EchoServerError : Error {