Add support to MultiFields

[bruno-lopes]

Hello,

I read the documentation of this plugin, and didn't find a way to define my custom multi fields as defined in https://www.elastic.co/guide/en/elasticsearch/reference/1.4/_multi_fields.html.

I know that is possible to use field_name multi_field: true, but it generate a field with the name untouched, which is not analyzed. But I want to do something like this (https://www.elastic.co/guide/en/elasticsearch/guide/current/sorting-collations.html#_unicode_sorting).

Is there a way to do that now? If not, will it be implemented? A think a nice syntax would be this way:

field_name fields = [
    raw: [type: 'string', index: 'not_analyzed' ],
    sort: [type: 'string', analyzer: 'my_sort']
]