[STORE] Added @mymodel.id= setter method

(For example, it seems FactoryGirl is setting attributes using instance setter methods...)

Closes elastic#149

Author: vhyza

elasticsearch-persistence/lib/elasticsearch/persistence/model/base.rb

@@ -25,6 +25,12 @@ def id
             @_id
           end; alias :_id :id
 
+          # Set the document `_id`
+          #
+          def id=(value)
+            @_id = value
+          end; alias :_id= :id=
+
           # Return the document `_index`
           #
           def _index

elasticsearch-persistence/test/unit/model_base_test.rb

@@ -27,6 +27,14 @@ class DummyBaseModel
       assert_equal 2, m.id
     end
 
+    should "set the ID using setter method" do
+      m = DummyBaseModel.new id: 1
+      assert_equal 1, m.id
+
+      m.id = 2
+      assert_equal 2, m.id
+    end
+
     should "have ID in attributes" do
       m = DummyBaseModel.new id: 1, name: 'Test'
       assert_equal 1, m.attributes[:id]