T5: Module builder discovery

[Hugo Palma]

I couldn't find in the docs how Tapestry finds the module builder(s) for 
the running application. I can see that for packaged modules it gets the 
info from META-INF, but what are the rules for the application provided 
module builders ?

I started testing and i could see that AppModule class gets picked up 
but App2Module doesn't. That's when i decided to ask here for the rules 
as i'm sure if i started guessing i'd probably miss something.