Update kotlin and build tools

.travis.yml

@@ -1,7 +1,7 @@
 language: android
 android:
   components:
-  - build-tools-27.0.3
+  - build-tools-28.0.3
   - android-27
   - extra-android-m2repository
   - extra-google-m2repository

app/build.gradle

@@ -30,7 +30,7 @@ ext {
 
 android {
     compileSdkVersion 27
-    buildToolsVersion '27.0.3'
+    buildToolsVersion '28.0.3'
     publishNonDefault true
 
     defaultConfig {
@@ -236,7 +236,7 @@ dependencies {
 }
 
 buildscript {
-    ext.kotlin_version = '1.2.60'
+    ext.kotlin_version = '1.2.71'
     repositories {
         mavenCentral()
     }