Add height to /blocks/seq/{from}/{to} API method

close #104

Author: catena2w

scorex-transaction/src/main/scala/scorex/api/http/BlocksApiRoute.scala

@@ -135,7 +135,8 @@ case class BlocksApiRoute(override val application: Application)(implicit val co
           case blockchain: BlockChain =>
             JsArray(
               (start to end).map { height =>
-                blockchain.blockAt(height).map(_.json).getOrElse(Json.obj("error" -> s"No block at height $height"))
+                blockchain.blockAt(height).map(_.json + ("height" -> Json.toJson(height)))
+                  .getOrElse(Json.obj("error" -> s"No block at height $height"))
               })
           case _ =>
             Json.obj("status" -> "error", "details" -> "Not available for other option than linear blockchain")

src/test/scala/scorex/lagonaki/integration/api/BlockAPISpecification.scala

@@ -14,7 +14,7 @@ class BlockAPISpecification extends FunSuite with Matchers with TransactionTesti
   val history = application.blockStorage.history
   val genesis = history.genesis
 
-  if (history.height() < 2) {
+  while (history.height() < 3) {
     application.blockStorage.appendBlock(genValidBlock())
   }
   val last = history.lastBlock
@@ -28,6 +28,8 @@ class BlockAPISpecification extends FunSuite with Matchers with TransactionTesti
     val response = GET.request(s"/blocks/seq/1/3")
     checkGenesis(response(0).as[JsValue])
     checkBlock(response(1).as[JsValue])
+    (response(1) \ "height").as[Int] shouldBe 2
+    (response(2) \ "height").as[Int] shouldBe 3
   }
 
   test("GET /blocks/last API route") {