Gradle build script clean-up

build.gradle

@@ -8,7 +8,6 @@ buildscript {
         jcenter{ url "http://jcenter.bintray.com/" }
     }
     dependencies {
-        classpath 'de.richsource.gradle.plugins:gwt-gradle-plugin:0.6'
         classpath 'com.android.tools.build:gradle:2.0.0'
         classpath 'org.robovm:robovm-gradle-plugin:1.12.0'
         classpath 'de.felixschulze.gradle:gradle-spoon-plugin:2.1'
@@ -59,9 +58,6 @@ allprojects {
 		gdxUtilsVersion = '0.13.2'
 	    mbassadorVersion = '1.2.0'
         roboVMVersion = '1.12.0'
-        box2DLightsVersion = '1.4'
-        ashleyVersion = '1.6.0'
-        aiVersion = '1.6.0'
         sqlDroidVersion = '1.0.3'
         sqlLiteJdbcVersion = '3.8.10.1'
         guavaVersion = '18.0'