Add mode to _currentScheme

[EtgarSH]

In order to determine if we are in debug or release mode, we need to add a key to the _currentScheme in simulator.js.

Something like:

{
    app: 'ios/build/Build/Products/Debug-iphonesimulator/example.app',
    mode: 'debug',
    device: 'iPhone 6s, iOS 9.3'
}

[LeoNatan]

@rotemmiz I think this can be closed as part of CLI tools.

[rotemmiz]

I am not sure there's a use case for this extra param. Can anyone elaborate?

[rotemmiz]

new configurations api should nail this requirement as well.