adds github build/test action

Signed-off-by: Emily Casey <ecasey@pivotal.io>

.github/workflows/build.yml

@@ -0,0 +1,17 @@
+name: build
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-java@v1
+      - name: Build
+        run: ./mvnw package