etherpad-lite: Don't write .ep_initialized in source directories

In my installation I install Etherpad without giving write permissions to the node processor over the source directory. It seems this is a problem because Etherpad tries to write to four places:

• APIKEY.txt (OK, I can generate this in advance)
• SESSIONKEY.txt (I can generate this as well)
• var/ (this is easy to make writable by node process)
• .ep_initialized in each plugin directory – this is hard to do without giving write access to all plugin code

So why is .ep_initialized needed? It seems it is only created once, but never really cleaned up?