serve: Refactoring and fixes to be able to serve taxonomy pages. * Page sources' `findPagePath` is renamed to `findPageFactory`, so that it also returns source metadata. * Page refs now store possible hits more properly, and use the previous point to also store metadata. As a result, they can also return a proper factory. * Implement `findPageFactory` correctly in all built-in sources. * When the Chef server matches a taxonomy page, get the source metadata from the page ref in order to make a more proper page. * Make the `getRoute(s)` functions explicitely say if they want taxonomy routes or not.

--- a/piecrust/commands/builtin/scaffolding.py	Sun Apr 26 08:34:27 2015 -0700
+++ b/piecrust/commands/builtin/scaffolding.py	Sun Apr 26 15:07:40 2015 -0700
@@ -64,8 +64,8 @@
         app = ctx.app
         source = ctx.args.source
         metadata = source.buildMetadata(ctx.args)
-        rel_path, metadata = source.findPagePath(metadata, MODE_CREATING)
-        path = source.resolveRef(rel_path)
+        factory = source.findPageFactory(metadata, MODE_CREATING)
+        path = factory.path
         name, ext = os.path.splitext(path)
         if ext == '.*':
             path = '%s.%s' % (