Update to sbt-s3 0.9

See scala/scala-jenkins-infra#82

Author: adriaanm

project/plugins.sbt

@@ -2,7 +2,7 @@ scalacOptions ++= Seq("-deprecation", "-feature", "-Xlint")
 
 addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % "1.0.6")
 
-addSbtPlugin("com.typesafe.sbt" % "sbt-s3" % "0.8")
+addSbtPlugin("com.typesafe.sbt" % "sbt-s3" % "0.9")
 
 // git plugin
 resolvers += "jgit-repo" at "http://download.eclipse.org/jgit/maven"