Enabled TravisCI (just building, no tests).

.travis.yml

@@ -0,0 +1,12 @@
+language: android
+dist: trusty
+
+android:
+  components:
+    - build-tools-28.0.3
+    - android-28
+
+script:
+  - ./gradlew build
+  #TODO: When all tests are passing, CI should also execute them.
+  #- ./gradlew connectedCheck

build.gradle

@@ -74,6 +74,11 @@ android {
     applicationVariants.all { variant ->
         variant.resValue "string", "applicationId", variant.applicationId
     }
+
+    //TODO: Should be removed (when LINT does not throw any errors).
+    lintOptions {
+        abortOnError false
+    }
 }
 
 dependencies {