Removed some duplicate code and fixed some naming

Author: gregbell

spec/unit/resource/page_presenters_spec.rb

@@ -9,7 +9,7 @@
     resource.page_presenters.should == {}
   end
 
-  it "should add a page config" do
+  it "should add a page presenter" do
     page_presenter = ActiveAdmin::PagePresenter.new
     resource.set_page_presenter(:index, page_presenter)
     resource.page_presenters[:index].should == page_presenter

spec/unit/resource_spec.rb

@@ -127,18 +127,6 @@ class ::News; def self.has_many(*); end end
       end
     end
 
-    describe "page configs" do
-      context "when initialized" do
-        it "should be empty" do
-          config.page_presenters.should == {}
-        end
-      end
-      it "should be set-able" do
-        config.page_presenters[:index] = "hello world"
-        config.page_presenters[:index].should == "hello world"
-      end
-    end
-
     describe "scoping" do
       context "when using a block" do
         before do