force scalaz-stream, netty-http-pipelining dependencies version which is available on maven central.

Currently, `sbt package` fail because of following missing dependencies.

1. "org.scalaz.stream" % "scalaz-stream_2.11" % "0.7a",
2. "com.typesafe.netty" % "netty-http-pipelining" % "1.1.2"

we should add following line in root build.sbt.

libraryDependencies ++= Seq(
    "org.scalaz.stream" % "scalaz-stream_2.11" % "0.8.4a",
    "com.typesafe.netty" % "netty-http-pipelining" % "1.1.4"
  ),