add support for different languages

[maxwellobi]

Currently, SpeechRecognition uses a language model based on free-form speech recognition. See here.
By specifying EXTRA_LANGUAGE_PREFERENCE we can provide an option to set the preferred language, from a list of device installed languages, to listen and translate on.

[puneetks]

Hi Maxwell,

I have tried your sample code but in case of offline it is not working