make Page#data call safe

lib/gollum/page.rb

@@ -27,7 +27,7 @@ module Gollum
     #
     # Returns the String data.
     def data
-      self.blob.data
+      self.blob.data rescue nil
     end
 
     # Find a page in the given Gollum repo.

test/test_page.rb

@@ -5,6 +5,11 @@ context "Page" do
     @wiki = Gollum::Wiki.new(testpath("examples/lotr.git"))
   end
 
+  test "new page" do
+    page = Gollum::Page.new(@wiki)
+    assert_nil page.data
+  end
+
   test "formatted page" do
     page = @wiki.formatted_page('Bilbo Baggins')
     assert_equal Gollum::Page, page.class