Fix ShopsSpec/AsyncActivateTest: the wrapping transactional needed to be removed.

The following spec shows in detail what works and what does not work:

    import org.specs2.mutable._
    import org.specs2.runner._
    import org.junit.runner._
    import play.api.test._
    import play.api.test.Helpers._
    import net.fwbrasil.activate.ActivateContext
    import net.fwbrasil.activate.test._
    import scala.concurrent.Future

    @RunWith(classOf[JUnitRunner])
    class ShopsSpec2 extends Specification
      with DefaultAwaitTimeout with FutureAwaits {

      def fakeApp = FakeApplication(
        // withGlobal = Some(new GlobalSettings {}),
        additionalPlugins = Seq("net.fwbrasil.activate.play.ActivatePlayPlugin"))

      def newShop(name: String, active: Boolean = false) = new Shop(name, "url", "queryUrlTemplate", None, active, "item", "name", "price", "imageUrl", "detailsUrl")

      def withTx[T](f: => T)(implicit ctx: ActivateContext): T = {
        import ctx._
        val transaction = new Transaction
        try {
          transactional(transaction)(f)
        } finally transaction.rollback
      }

      "Shop model" should {

        // Fails because of the wrapping transaction
        "be created and selected async (fails)" in {
          running(fakeApp) {
            import shopPersistenceContext._
            withTx {
              val item = transactional {
                newShop("shop1")
              }
              val shops = await(asyncTransactionalChain { implicit ctx =>
                asyncSelect[Shop] where (_.id :== item.id)
              })
              shops must contain(item)
            }
          }
        }

        // No wrapping tx, this works
        "be created and selected async" in {
          running(fakeApp) {
            import shopPersistenceContext._
            val item = transactional {
              newShop("shop1")
            }
            val shops = await(asyncTransactionalChain { implicit ctx =>
              asyncSelect[Shop] where (_.id :== item.id)
            })
            shops must contain(item)
          }
        }

      }

    }