Update sample build.gradle

Update sample build.gradle to SDK 21, plugin 1.1; add missing assets folder

Author: Paul Verest

sample/build.gradle

@@ -1,33 +1,34 @@
 buildscript {
     repositories {
-        mavenCentral()
+        jcenter()
     }
 
     dependencies {
-        classpath 'com.android.tools.build:gradle:0.6.+'
+        classpath 'com.android.tools.build:gradle:1.1.+'
     }
 }
 
 
-apply plugin: 'android'
+apply plugin: 'com.android.application'
 
 repositories {
-    mavenCentral()
+    jcenter()
 }
 
 dependencies {
     compile fileTree(dir: 'libs', include: '*.jar')
 }
 
 android {
-    compileSdkVersion 19
-    buildToolsVersion "18.1"
+    compileSdkVersion 21
+    buildToolsVersion "21.1.2"
 
     sourceSets {
         main {
             manifest.srcFile 'AndroidManifest.xml'
             java.srcDirs = ['src']
             res.srcDirs = ['res']
+            assets.srcDirs = ['assets']
         }
     }
 }