Don't appcache empty file pages/blog.html

This causes a bug when using the android browser. Specifically, because
pages/blog.html is appcached it always prefers the appcached version and
thus loads an empty blog (unless you explicit request pages/blog1.html)

This empty file is required while generating the navigation. There seems
to be no way to not write a file once within the Rules monad (or at
least it's not simple).

Signed-off-by: Collin J. Doering <rekahsoft@gmail.com>

src/site.hs

@@ -114,7 +114,7 @@ main = do
                       ("posts/**" .&&. hasNoVersion)
                       (\n -> fromCapture "pages/blog*.html" (show n))
     
-    pageIds <- getMatches "pages/**"
+    pageIds <- getMatches ("pages/**" .&&. complement "pages/blog.markdown")
     fontIds <- getMatches "fonts/**"
     imageIds <- getMatches "images/**"
     cssIds <- getMatches "css/**"