added cross build support for 2.9.1

Author: debasishg

project/ScalaRedisProject.scala

@@ -9,7 +9,8 @@ object ScalaRedisProject extends Build
   lazy val commonSettings: Seq[Setting[_]] = Seq(
     organization := "net.debasishg",
     version := "2.7",
-    scalaVersion := "2.9.2",
+    // scalaVersion := "2.9.2",
+    crossScalaVersions := Seq("2.9.2", "2.9.1"),
     scalacOptions ++= Seq("-deprecation", "-unchecked"),
     resolvers ++= Seq(twitterRepo)
   )