Restructure public side of network service.

This CL goes from this:
  //mojo/services/public/cpp/network
  //mojo/services/public/interfaces/network

to this:
  //mojo/services/network/public/cpp
  //mojo/services/network/public/interfaces

This CL also makes the Mojo-side changes required to roll this change into
Chromium.

TBR=beng

Review URL: https://codereview.chromium.org/789243002
diff --git a/mojo/services/network/tcp_server_socket_impl.h b/mojo/services/network/tcp_server_socket_impl.h
index 26d4942..0009951 100644
--- a/mojo/services/network/tcp_server_socket_impl.h
+++ b/mojo/services/network/tcp_server_socket_impl.h
@@ -7,7 +7,7 @@
 
 #include "base/memory/scoped_ptr.h"
 #include "mojo/public/cpp/bindings/interface_impl.h"
-#include "mojo/services/public/interfaces/network/tcp_server_socket.mojom.h"
+#include "mojo/services/network/public/interfaces/tcp_server_socket.mojom.h"
 #include "net/base/ip_endpoint.h"
 #include "net/socket/tcp_socket.h"