Upgrade jackson to 2.7.1

Author: komamitsu

build.sbt

@@ -97,7 +97,7 @@ lazy val msgpackJackson = Project(id = "msgpack-jackson", base = file("msgpack-j
  name := "jackson-dataformat-msgpack",
  description := "Jackson extension that adds support for MessagePack",
  libraryDependencies ++= Seq(
- "com.fasterxml.jackson.core" % "jackson-databind" % "2.6.3",
+ "com.fasterxml.jackson.core" % "jackson-databind" % "2.7.1",
  junitInterface,
  "org.apache.commons" % "commons-math3" % "3.4.1" % "test"
  ),