Bump the version to 3.0.0-RC4 and fix the link to source tag name.

Author: bvenners

project/scalatest.scala

@@ -21,11 +21,11 @@ object ScalatestBuild extends Build {
   // > ++ 2.10.5
   val buildScalaVersion = "2.11.8"
 
-  val releaseVersion = "3.0.0-RC3"
+  val releaseVersion = "3.0.0-RC4"
 
   val scalacheckVersion = "1.13.1"
 
-  val githubTag = "release-3.0.0-M16-SNAP4-for-scala-2.11-and-2.10" // for scaladoc source urls
+  val githubTag = "release-3.0.0-RC4" // for scaladoc source urls
 
   val scalatestDocSourceUrl =
     "https://github.com/scalatest/scalatest/tree/"+ githubTag +