added source and targetCompatibility information

build.gradle

@@ -18,6 +18,8 @@ group = 'it.unibz.inf.isochrone'
 version = '0.2-SNAPSHOT'
 
 description = 'PhD project of Nikolaus Krismer'
+sourceCompatibility=1.7
+targetCompatibility=1.7
 
 def getDate() {
 	def date = new Date()