Added Evan Ricafort to AUTHORS (XSS vulnerability). Thanks!

Evan found a critical vulnerability in GeoNode related to XSS and alerted the core developers privately.

As we have done in the past with security researches, here is his contact information:

Twitter: @robinhood0x00
Website: www.evanricafort.com
Report:  Input XSS Payload in the Search Bar and wait until it stops searching, dont click the search or hit enter in your keyboard. just wait until it stops loading and see the result
Merge branch 'master' of github.com:GeoNode/geonode