Allow search by person name i.e. 'First Last'

On a number of occasions I've searched for someone by first and last name like "John Doe" in MPDX only to find no results, when "Doe, John" or "John" or "Doe" do give results. This fixes that by searching by the person's first and last name if there are two words in the search query.
is the first_name.present? test necessary? how could there be a last name but no first name? 

And what about the comma if someone puts in Last, First? Will that be a problem?