Fix to ticket 2.

When updating the last page revision in the "continuous revision" case, created_at should be used
instead of Time.now.

app/models/page.rb

@@ -20,7 +20,7 @@ class Page
     # by the same author, not more than 30 minutes ago, then update the last revision instead of
     # creating a new one
     if !@revisions.empty? && continous_revision?(created_at, author)
-      @revisions.last.created_at = Time.now
+      @revisions.last.created_at = created_at
       @revisions.last.content    = content
       @revisions.last.clear_display_cache
     else

test/unit/page_test.rb

@@ -64,6 +64,7 @@ class PageTest < Test::Unit::TestCase
     @page.revise("HisWay would be MyWay in kinda update", Time.local(2004, 4, 4, 16, 57), "MarianneSyhler")
     assert_equal 2, @page.revisions.length
     assert_equal "HisWay would be MyWay in kinda update", @page.revisions.last.content
+    assert_equal Time.local(2004, 4, 4, 16, 57), @page.revisions.last.created_at
 
     @page.revise("HisWay would be MyWay in the house", Time.local(2004, 4, 4, 16, 58), "DavidHeinemeierHansson")
     assert_equal 3, @page.revisions.length