updating travis build script to use java 1.8
updating travis build script to use java 1.8

nigel-v-thomas/WWARN-Maps-Surveyor,nigel-v-thomas/WWARN-Maps-Surveyor,WorldwideAntimalarialResistanceNetwork/WWARN-Maps-Surveyor,WorldwideAntimalarialResistanceNetwork/WWARN-Maps-Surveyor,WorldwideAntimalarialResistanceNetwork/WWARN-Maps-Surveyor,nigel-v-thomas/WWARN-Maps-Surveyor