Support apachesolr_user

The module is (yet) not on d.o : http://github.com/SupermanScott/apachesolr_users
Project ist pretty well written and works pretty good.

Worked until i installed apachesolr_mutlilingual, so i expect it to be the cause. There is a slightly chance that the issue is coming from my changed schem / solrconfig but i checked it already, expecting it to work.

The query looks fine, fields are filled but still no results (somehow similar to attachments).

Will debug this further tomorrow.