Remove page file dir from frontend. Resolves #1052 #1241 (#1369)

* Remove all references to page_file_dir. Use new method signature for Wiki#page. Refactor helpers.
* Use write_file for uploads
* Refactor /pages route

Rakefile

@@ -71,6 +71,7 @@ Rake::TestTask.new(:test) do |test|
   test.libs << 'lib' << 'test' << '.'
   test.pattern = 'test/**/test_*.rb'
   test.verbose = true
+  test.warning = false
 end
 
 desc "Generate RCov test coverage and open in your browser"