Bumped version of gRPC to 1.3.1

Change-Id: I7798476bd443a796e0e6a6e149ab8f66435ba4fa
diff --git a/incubator/protobuf/models/BUCK b/incubator/protobuf/models/BUCK
index 81a9b25..2fc2d4b 100644
--- a/incubator/protobuf/models/BUCK
+++ b/incubator/protobuf/models/BUCK
@@ -1,17 +1,18 @@
+GRPC_VER = '1.3.1'
 
 COMPILE_DEPS = [
     '//lib:CORE_DEPS',
     ':onos-incubator-protobuf-models-proto',
     '//lib:protobuf-java-3.2.0',
     '//lib:GRPC_1.3',
-    '//incubator/grpc-dependencies:grpc-core-repkg-1.3.0'
+    '//incubator/grpc-dependencies:grpc-core-repkg-' + GRPC_VER
 ]
 
 GRPC_DEPS = [
     '//lib:GRPC_1.3',
     '//lib:protobuf-java-3.2.0',
     '//lib:guava',
-    '//incubator/grpc-dependencies:grpc-core-repkg-1.3.0'
+    '//incubator/grpc-dependencies:grpc-core-repkg-' + GRPC_VER
 ]
 
 BUNDLES = [