Create all presented Subcontexts

I make a context class in my features/bootstrap directory which implements DrupalSubContextIterface. It is loaded by Behat, but DrupalExtenson don't make a SubContext object in the initializeSubContexts() function. When I add an empty behat.inc file (eg.: something.behat.inc) anywhere where DrupalExtension found it, my context class created and I can use sentences.

I suggest load the files in the DrupalAwareInitializer instead of DrupalContext and call initializeSubContexts() funtion always, then DrupalExtension will use subcontext in the features/bootstrap directory automatically.