fixes #208 - use nested_attributes for lookup parameters

fixes #141 - add support to extlookup kind of queries through foreman
usage:
wget -q -O - "http://foreman/lookup?key=ntpserver&order[]=my.domain&order[]=common"
if you want it in YAML, just add:
wget -q -O - "http://foreman/lookup?key=ntpserver&order[]=my.domain&order[]=common&format=yml"