update version Android playground version to 21. The latest binary apk version is 21.
diff --git a/android/playground/build.gradle b/android/playground/build.gradle
index 5f16c34..b66dd9b 100755
--- a/android/playground/build.gradle
+++ b/android/playground/build.gradle
@@ -13,8 +13,8 @@
applicationId "org.apache.weex"
minSdkVersion project.minSdkVersion
targetSdkVersion project.targetSdkVersion
- versionCode 20
- versionName "0.20.0"
+ versionCode 21
+ versionName "0.21.0"
testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
multiDexEnabled true
ndk{