Build: centralise the place for all versions.

app/build.gradle

@@ -12,8 +12,8 @@ apply plugin: 'kotlin-android'
 apply plugin: 'kotlin-kapt'
 
 android {
-    compileSdkVersion 28
+    compileSdkVersion rootProject.ext.compileSdkVersion
-    buildToolsVersion '28.0.3'
+    buildToolsVersion rootProject.ext.buildToolsVersion
 
     defaultConfig {
         applicationId "com.etesync.syncadapter"

build.gradle

@@ -6,16 +6,24 @@
  * http://www.gnu.org/licenses/gpl.html
  */
 
+ext {
+    kotlin_version = '1.2.71'
+    gradle_version = '3.2.1'
+    compileSdkVersion = 28
+    buildToolsVersion = '28.0.3'
+}
+
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 buildscript {
-    ext.kotlin_version = '1.3.11'
+    ext.kotlin_version = '1.2.71'
+    ext.gradle_version = '3.2.1'
 
     repositories {
         jcenter()
         google()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:3.2.1'
+        classpath "com.android.tools.build:gradle:$gradle_version"
         classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
     }
 }
@@ -30,4 +38,5 @@ allprojects {
     }
 }
 
+
 apply plugin: 'android-reporting'

cert4android

@@ -1 +1 @@
-Subproject commit b84178da93eefc40aa09e360bc39da60ae371820
+Subproject commit 594fcba6289bc7812c1dccc3a84c7e677f29dd7a

ical4android

@@ -1 +1 @@
-Subproject commit 2437b0b7aedf4fa1907a88c72781cff4c8291e40
+Subproject commit 485ad1bfe8af3db40e8ddac056b56e4b505410de

vcard4android

@@ -1 +1 @@
-Subproject commit 42d5cc3f8b16c628fa13a5a3b0f211e6660fb084
+Subproject commit 66e08cd395dea798e833cf30f0c396ad6a87c9ea