changed the netty-codec-http2 depdendency to released version

* 4.1.0.Beta5
* available on maven central http://search.maven.org/#artifactdetails%7Cio.netty%7Cnetty-codec-http2%7C4.1.0.Beta5%7Cjar
* git tag release 4.1.0.Beta5
diff --git a/build.gradle b/build.gradle
index 6d0da2e..6fe645f 100644
--- a/build.gradle
+++ b/build.gradle
@@ -87,9 +87,7 @@
                 protobuf_nano: "com.google.protobuf.nano:protobuf-javanano:${protobufVersion}",
                 protobuf_plugin: 'com.google.protobuf:protobuf-gradle-plugin:0.3.1',
 
-                // TODO: Unreleased dependencies.
-                // These must already be installed in the local maven repository.
-                netty: 'io.netty:netty-codec-http2:4.1.0.Beta5-SNAPSHOT',
+                netty: 'io.netty:netty-codec-http2:4.1.0.Beta5',
 
                 // Test dependencies.
                 junit: 'junit:junit:4.11',