blow away the view cache between specs

One of our cukes was failing because Rails caches templates and the
differing format seems not to be enough to invalidate it automatically,
I'm going to open a Rails patch for this but in the mean time this fixes
that cuke.

Author: JonRowe

lib/rspec/rails/example/view_example_group.rb

@@ -152,6 +152,9 @@ def _include_controller_helpers
           view.lookup_context.prefixes << _controller_path
         end
 
+        # fixes bug with differing formats
+        view.lookup_context.view_paths.each(&:clear_cache)
+
         controller.controller_path = _controller_path
         controller.request.path_parameters[:controller] = _controller_path
         controller.request.path_parameters[:action]     = _inferred_action unless _inferred_action =~ /^_/