Adding support for TLS connections for gRPC clients

This patch uses BoringSSL to negotiate TLS sessions under the hood.

Change-Id: I45b6871eb341bd67a230035a930f6a016d105e97
diff --git a/protocols/grpc/ctl/BUILD b/protocols/grpc/ctl/BUILD
index ac0703d..475a90e 100644
--- a/protocols/grpc/ctl/BUILD
+++ b/protocols/grpc/ctl/BUILD
@@ -3,6 +3,7 @@
     "//protocols/grpc/proto:onos-protocols-grpc-proto",
     "@io_grpc_grpc_java//core",
     "@io_grpc_grpc_java//netty",
+    "@io_netty_netty_handler//jar",
 ]
 
 osgi_jar(