upgrade API level 28.

.travis.yml

@@ -15,10 +15,10 @@ android:
     - tools
 
     # The BuildTools version used
-    - build-tools-27.0.3
+    - build-tools-28.0.3
 
     # The SDK version used
-    - android-27
+    - android-28
 
 before_cache:
   - rm -f $HOME/.gradle/caches/modules-2/modules-2.lock

app/build.gradle

@@ -6,12 +6,12 @@ android {
         disable 'ExtraTranslation'
     }
 
-    compileSdkVersion 27
+    compileSdkVersion 28
 
     defaultConfig {
         applicationId "ch.blinkenlights.android.vanilla"
         minSdkVersion 15
-        targetSdkVersion 27
+        targetSdkVersion 28
     }
 
     buildTypes {
@@ -28,6 +28,7 @@ android {
 }
 
 dependencies {
-    implementation 'com.android.support:support-core-ui:27.1.1'
-    compileOnly 'com.android.support:support-annotations:27.1.1'
+    implementation 'com.android.support:support-core-ui:28.0.0'
+    compileOnly 'com.android.support:support-annotations:28.0.0'
+    compileOnly 'junit:junit:4.12'
 }