Enable Travis CI builds of APRSdroid

Specify correct components for Travis CI to install

.travis.yml

@@ -0,0 +1,25 @@
+language: android
+dist: trusty
+android:
+  components:
+    - tools
+    - platform-tools
+
+    - build-tools-28.0.3
+    - android-28
+
+    - sys-img-x86-android-26
+
+  licenses:
+    - 'android-sdk-preview-license-52d11cd2'
+    - 'android-sdk-license-.+'
+
+before_cache:
+  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
+  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
+
+cache:
+  directories:
+    - $HOME/.gradle/caches/
+    - $HOME/.gradle/wrapper/
+    - $HOME/.android/build-cache