Add building of pull requests via GitHub Actions

.github/workflows/maven.yml

@@ -0,0 +1,21 @@
+name: Maven Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        java: [8, 11]
+
+    name: Java ${{ matrix.java }}
+
+    steps:
+    - uses: actions/checkout@v1
+    - uses: actions/setup-java@v1
+      with:
+        java-version: ${{ matrix.java }}
+    - run: java -version
+    - run: mvn package javadoc:jar source:jar