Support for Mongoid localized fields

[Startouf]

Is it possible to use a fulltext search on a translated field ? Knowing the fields behaves like a hash, it it possible to either

• 1: enable lookup for all languages at the same time,
• 2: given a language (ie I18n.locale), autocomplete only for that specific language ?

[dblock]

This would require some work, feel free to contribute.

[dblock]

Superset of #14