remove unnecessary information from task

python/educational-core/src/com/jetbrains/edu/learning/courseFormat/tasks/Task.java

@@ -50,7 +50,6 @@ public abstract class Task implements StudyItem {
 
   @Transient private Lesson myLesson;
   @Expose @SerializedName("update_date") private Date myUpdateDate;
-  @Expose @SerializedName("position") private int myPosition;
 
   public Task() {}
 
@@ -277,10 +276,7 @@ public abstract class Task implements StudyItem {
   }
 
   public int getPosition() {
-    return myPosition;
-  }
-
-  public void setPosition(int position) {
-    myPosition = position;
+    final Lesson lesson = getLesson();
+    return lesson.getTaskList().indexOf(this) + 1;
   }
 }

python/educational-core/src/com/jetbrains/edu/learning/stepic/EduStepicConnector.java

@@ -323,7 +323,6 @@ public class EduStepicConnector {
     task.setStepId(stepicId);
     task.setUpdateDate(step.update_date);
     task.setName(block.options != null ? block.options.title : (PYCHARM_PREFIX + CURRENT_VERSION));
-    task.setPosition(step.position);
 
     for (StepicWrappers.FileWrapper wrapper : block.options.test) {
       task.addTestsTexts(wrapper.name, wrapper.text);