Map user bundle machine name to user label

When there's no entities provided as options in the facetapi_map_bundle function (facetapi.callbacks.inc), the default behaviour would be to only map the node bundles' machine names with labels. This would cause the user bundle to be overlooked.

The side effect of this (of what I have stumbled upon) is the lack of multilingual support for the user bundle label.

/ Kallehauge