Allow parameters for translation config

[Pascal Moser]

Q	A
Bug report?	no
Feature request?	yes
BC Break report?	no
RFC?	no

Allow yaml parameters for i18n.translations and i18n.zones.zonexy.config.translations.

Example yaml config:

parameters:
    i18n_translations:
        -   key: 'event'
            values:
                de: 'veranstaltung'
                fr: 'evenement'
                en: 'event'

i18n:
    translations: '%i18n_translations%'
    zones:
        zonexy:
            config:
                translations: '%i18n_translations%'

Current Exception:
Invalid type for path "i18n.translations". Expected "array", but got "string"