override TCCL for test invocation

Author: Andrei-Pozolotin

org.scala-ide.sdt.scalatest/src/scala/tools/eclipse/scalatest/launching/ScalaTestLauncher.scala

@@ -50,6 +50,8 @@ object ScalaTestLauncher {
       val urls = classpath.map { cp => new File(cp.toString).toURI.toURL }.toArray
       val loader = new URLClassLoader(urls, ClassLoader.getSystemClassLoader)
 
+      Thread.currentThread().setContextClassLoader(loader)
+      
       val runnerClass =  loader.loadClass("org.scalatest.tools.Runner")
       val mainMethod = runnerClass.getMethod("main", args.getClass()) //$NON-NLS-1$
       mainMethod.setAccessible(true)