Update build to sbt 1.2.8

Author: ashawley

project/build.properties

@@ -1 +1 @@
-sbt.version=0.13.17
+sbt.version=1.2.8

project/plugins.sbt

@@ -1,13 +1,8 @@
-if (System.getProperty("java.version").startsWith("1."))
-  Seq()
-else
-  // override to version that works on Java 9,
-  // see https://github.com/scala/sbt-scala-module/issues/35
-  Seq(addSbtPlugin("com.typesafe.sbt" % "sbt-osgi" % "0.9.3"))
+addSbtPlugin("com.typesafe.sbt" % "sbt-osgi" % "0.9.5")
 
 val scalaJSVersion =
   Option(System.getenv("SCALAJS_VERSION")).filter(_.nonEmpty).getOrElse("0.6.27")
 
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % scalaJSVersion)
 addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "0.6.0")
-addSbtPlugin("org.scala-lang.modules" % "sbt-scala-module" % "1.0.14")
+addSbtPlugin("org.scala-lang.modules" % "sbt-scala-module" % "2.0.0")