Revert "Sbt 0.13.15 -> 1.2.6."

This reverts commit c837620

build.sbt

@@ -2,9 +2,6 @@ import sbt.Keys._
 
 lazy val baseVersion = "3.5.9"
 
-lazy val akkaVersion = settingKey[String]("Version of Akka compiled against")
-akkaVersion := "2.3.0"
-
 // See crossrelease.sh for valid combinations of akkaVersion and crossScalaVersion.
 
 // Developed against 2.3.* (2.4.* for scala 2.12), see crossrelease.sh for all tested and build versions.
@@ -27,7 +24,7 @@ version := {
 description := {
   val av = akkaVersion.value
   val akkaDescription = if (av.nonEmpty) "Akka " + av +" and " else ""
-  "metrics-scala for " + akkaDescription + "Scala " + CrossVersion.binaryScalaVersion(scalaVersion.value)
+  "metrics-scala for " + akkaDescription + "Scala " + sbt.cross.CrossVersionUtil.binaryScalaVersion(scalaVersion.value)
 }
 
 // Developed against 2.11, see crossrelease.sh for all tested and build versions.

project/build.properties

@@ -1 +1 @@
-sbt.version=1.2.6
+sbt.version=0.13.15

project/build.scala

@@ -0,0 +1,8 @@
+import sbt._
+import Keys._
+
+object MetricsScalaBuild extends Build {
+  lazy val akkaVersion = settingKey[String]("Version of Akka compiled against")
+
+  akkaVersion := "2.3.0"
+}