Added upload Travis CI stage that pushes artifacts for all build vari…

…ants (#20)

* Added upload Travis CI stage that pushes artifacts for all build variants.

* Fixed release condition and added an || true to ensure the script always has a 0 exit code.

* Updated upload jobs to output a log message if no release is needed.

.travis.yml

@@ -18,6 +18,24 @@ jobs:
       env: SPARK_VERSION=2.4.3
     - scala: 2.12.11
       env: SPARK_VERSION=2.4.3
+    # The upload stage is an inelegant way to automatically publish all artifact variants until the following Shipkit
+    # issue is resolved: https://github.com/mockito/shipkit/issues/858
+    - stage: upload
+      scala: 2.11.8
+      env: SPARK_VERSION=2.3.0
+      script: ./gradlew releaseNeeded | grep "Releasing"
+        && ./gradlew bintrayUpload -PscalaVersion=$TRAVIS_SCALA_VERSION -PsparkVersion=$SPARK_VERSION
+        || echo "No release needed.";
+    - scala: 2.11.8
+      env: SPARK_VERSION=2.4.3
+      script: ./gradlew releaseNeeded | grep "Releasing"
+        && ./gradlew bintrayUpload -PscalaVersion=$TRAVIS_SCALA_VERSION -PsparkVersion=$SPARK_VERSION
+        || echo "No release needed.";
+    - scala: 2.12.11
+      env: SPARK_VERSION=2.4.3
+      script: ./gradlew releaseNeeded | grep "Releasing"
+        && ./gradlew bintrayUpload -PscalaVersion=$TRAVIS_SCALA_VERSION -PsparkVersion=$SPARK_VERSION
+        || echo "No release needed.";
     - stage: release
       scala: 2.11.8
       env: SPARK_VERSION=2.3.0