A free-form lensing grid solution for A1689 with new multiple images

JMD acknowledges support of the consolider project CAD2010-00064 and AYA2012-39475-C02-01 funded by the Ministerio de Economia y Competitividad. KU acknowledges partial support from the National Science Council of Taiwan (grant NSC100-2112-M-001-008-MY3). MS acknowledges financial support from the agreement ASI/INAF/023/12/0. NB and TB acknowledge support of the grants AYA2010- 22111-C03-01 funded by the Ministerio de Economia y Competitividad and PEX/10-CFQM-6444 of the Junta de Andalucia.