Move data directory permission checks after data directory existence checks

I came across this while looking at #1128 It just moves the permissions checks after it makes sure the data directory exists.

However, what is this backup directory? I see no where else the enablebackup or backupdirectory config values are used in the code. And there's a TODO in there that I don't know anything about.

One more thing, do we really need to call checkServer for every single request? Nothing should be changing after the install. We should still call the permission checks for the config and data directory for each request though.

@karlitschek