Simplify conditional module dependency in sbt sample.

Per @adriaanm's suggestion, I boiled down the logic to its essence.
It still supports Scala 2.11 and newer versions.

Author: gkossakowski

README.md

@@ -15,15 +15,9 @@ This sample demonstrates how to conditionally depend on scala-xml module. If you
 libraryDependencies := {
   CrossVersion.partialVersion(scalaVersion.value) match {
     // if scala 2.11+ is used, add dependency on scala-xml module
-    case Some((_, scalaMajor)) =>
-      if (scalaMajor >= 11)
+    case Some((2, scalaMajor)) if scalaMajor >= 11 =>
         libraryDependencies.value :+ "org.scala-lang.modules" %% "scala-xml" % "1.0.0"
-      else
-        libraryDependencies.value
-    // ooops, we failed to parse scala version properly
-    case None =>
-      // fails to compile with: error: A setting cannot depend on a task
-      //streams.value.log.warn(s"Couldn't parse scala version: ${scalaVersion.value}. The dependency on xml module hasn't been added.")
+    case _ =>
       libraryDependencies.value
   }
 }

sbt-sample/build.sbt

@@ -13,15 +13,9 @@ scalaVersion := "2.11.0-RC1"
 libraryDependencies := {
   CrossVersion.partialVersion(scalaVersion.value) match {
     // if scala 2.11+ is used, add dependency on scala-xml module
-    case Some((_, scalaMajor)) =>
-      if (scalaMajor >= 11)
+    case Some((2, scalaMajor)) if scalaMajor >= 11 =>
         libraryDependencies.value :+ "org.scala-lang.modules" %% "scala-xml" % "1.0.0"
-      else
-        libraryDependencies.value
-    // ooops, we failed to parse scala version properly
-    case None =>
-      // fails to compile with: error: A setting cannot depend on a task
-      //streams.value.log.warn(s"Couldn't parse scala version: ${scalaVersion.value}. The dependency on xml module hasn't been added.")
+    case _ =>
       libraryDependencies.value
   }
 }