Comment out tests as fixed in ferrum master

Author: route

spec/features/driver_spec.rb

@@ -792,7 +792,7 @@ def create_screenshot(file, *args)
       end
     end
 
-    it "can clear memory cache" do
+    it "can clear memory cache", skip: "Fixed in ferrum master" do
       @driver.clear_memory_cache
 
       @session.visit("/cuprite/cacheable")