included file root

[luben]

Continuation of the #94, it's different problem but the setup is the same (so skipping the Scala/C++ code).

if we have the config files: test-1.conf:

Foo {
    foo = "foo"
}

Bar {
    include file("bar")                                                                                                                                                                        
}

bar.conf:

bar = "bar"
doubleBar = ${bar}

it fails the substitution with: "Could not resolve subtitution to a value: ${bar}".

If we use instead:

doubleBar = ${Bar.bar}

it works and the substitution is performed.

In the reference implementation (typesafe-config) both cases succeed.