Update build-tools version for gradle.

Change-Id: I12d25605b1491c515460dcccfd70fd7333f28f3b
diff --git a/build.gradle b/build.gradle
index d28959d..f8218fa 100644
--- a/build.gradle
+++ b/build.gradle
@@ -2,7 +2,7 @@
 
 android {
     compileSdkVersion 17
-    buildToolsVersion = 17
+    buildToolsVersion = '19.0.1'
 
     sourceSets {
         defaultConfig {