Upgrade libGdx and all related components to version 1.7.1.

Branch for anyone who is willing and have time to test it.

build.gradle

@@ -56,13 +56,13 @@ allprojects {
         applicationIdDevelSuffix = '.devel'
         applicationIdDevel = applicationIdRelease + applicationIdDevelSuffix
 
-        gdxVersion = '1.6.1'
-		gdxUtilsVersion = '0.13.1'
+        gdxVersion = '1.7.1'
+		gdxUtilsVersion = '0.13.2'
 	    mbassadorVersion = '1.2.0'
-        roboVMVersion = '1.2.0'
-        box2DLightsVersion = '1.3'
-        ashleyVersion = '1.3.1'
-        aiVersion = '1.4.0'
+        roboVMVersion = '1.9.0'
+        box2DLightsVersion = '1.4'
+        ashleyVersion = '1.6.0'
+        aiVersion = '1.6.0'
         sqlDroidVersion = '1.0.3'
         sqlLiteJdbcVersion = '3.8.10.1'
         guavaVersion = '18.0'