Text Search For Query New Design

Tests are outdated given the new design and I will re-write them. 

You changed the pattern from all the other module specializations. mango_selector_text would be more appropriate. Also, mango_selector_text:parse_selector/1 is a bit odd. You're not parsing it and selector is redundant. Perhaps, mango_selector_text:to_lucene_query/1? Or just to_lucene maybe.