update ES docs
Validate origin doesn't exist on upload (bug 878105)
Version uploaded while another version is PUBLIC_WAITING goes to wrong queue (bug 868526)

If an app is in PUBLIC_WAITING state, then:
- get_version() should return the current PUBLIC_WAITING version
- update_status() shouldn't erase PUBLIC_WAITING when there is a new version
- When new versions are uploaded for that app, it should go in the update queue
some atomicity to theme reuploading (bug 876819)
store cats as slugs in ES to fix linux app installs (bug 876293)