Issue #31: FIX learning-object thumbnail

app/controllers/v1/learning_objects_controller.rb

@@ -95,11 +95,16 @@ class V1::LearningObjectsController < ApplicationController
       publisher = LearningObjectPublisher.new(DspaceService.create_client)
       publisher.update_dspace(@learning_object)
 
+      render json: @learning_object, status: :ok
+    else
+      if lo_params[:thumbnail] != "null"
+        @learning_object.thumbnail = params[:thumbnail]
         render json: @learning_object, status: :ok
       else
         render json: @learning_object.errors, status: :unprocessable_entity
       end
     end
+  end
 
   # DELETE /learning_objects/1
   # DELETE /learning_objects/1.json