How to translate language in Symfony 2, according to accept language header?
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I have 

config.yml 

    #Here locale is en
    translator:      { fallback: %locale% }
    ...
    session:
        default_locale: %locale%

routing.yml

	AcmeDemoBundle_homepage:
	    pattern:  /{_locale}/index
	    defaults: { _controller: AcmeDemoBundle:Default:index, _locale: de}
	    requirements:
		_locale: en|de


So here by manually typing URL will lead   `/en/index` to  English and `/de/index` to German.

How we can make automatically go to german, if browser Accept language is de_DE or de(German), else go to english(all other browser Accept languages)?  