build.gradle: upgrade to the latest API 18.

android/build.gradle

@@ -3,15 +3,15 @@ buildscript {
 		mavenCentral()
 	}
 	dependencies {
-		classpath 'com.android.tools.build:gradle:0.4.2'
+		classpath 'com.android.tools.build:gradle:0.5.+'
 	}
 }
 
 apply plugin: 'android'
 
 android {
-	buildToolsVersion '17.0'
-	compileSdkVersion 17
+	buildToolsVersion '18.0'
+	compileSdkVersion 18
 
 	sourceSets {
 		main {