Add onceoff job to fix incorrect upload extensions.

app/jobs/onceoff/fix_invalid_upload_extensions.rb

@@ -0,0 +1,9 @@
+require_dependency "upload_fixer"
+
+module Jobs
+  class FixInvalidUploadExtensions < Jobs::Onceoff
+    def execute_onceoff(args)
+      UploadFixer.fix_all_extensions
+    end
+  end
+end