Fix Android build

it's same fix with #15400, #15605 but for 2.1 branch

platform/android/build.gradle.template

@@ -14,12 +14,13 @@ allprojects {
     repositories {
     	jcenter()
 	mavenCentral()
+	google()
 	$$GRADLE_REPOSITORY_URLS$$
     }
 }
 
 dependencies {
-	compile 'com.android.support:support-v4:23.+'  // can be removed if minSdkVersion 16 and modify DownloadNotification.java & V14CustomNotification.java
+	compile 'com.android.support:support-v4:27.+'  // can be removed if minSdkVersion 16 and modify DownloadNotification.java & V14CustomNotification.java
 	$$GRADLE_DEPENDENCIES$$
 }