Hello,
please be aware that in Alfresco 5.0, all out-of-the-box configuration resources are bundled WITHIN the JAR of the corresponding project, so almost all files that were once contained in the exploded WAR now reside in some /WEB-INF/lib/name-of.jar.
You can still override transformers.properties by adding the appropriate subsystem to your /alfresco/extension directory or using alfresco-global.properties. The original file should be contained in the alfresco-repository-5.0.b.jar.
The upload.post.js should be contained in the alfresco-remote-api-5.0.b.jar
Regards
Axel