Improve the search in series list to display the matches ordered by relevance

[iriadp]

Steps to reproduce it:

• Go to the backoffice, to the series view.
• Search for an expression with two or more words.

Actual behaviour: All the matches for each word will appear ordered by the publication date.
Expected behaviour: The matches should be ordered from the best match (results with all the words from the search we performed) to the results less relevant.