Allow host to be a regexp. useful for subdomains.

[makasim]

It helps us to configure router once for all cases, dev, staging, prod etc

jms_i18n_routing:
    default_locale: %locale%
    locales: ['sv', 'no']
    strategy: custom
    hosts:
        'sv': '/foo\.se|.*\.foo\.se/'
        'no': '/foo\.no|.*\.foo\.no/'