add github actions

.github/workflows/buildjar.yml

@@ -0,0 +1,36 @@
+name: Build CommandWhitelist Jar
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+    branches:
+      - master
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout Git repo
+        uses: actions/checkout@v1
+      - name: Restore Maven cache
+        uses: actions/cache@v1
+        with:
+          path: ~/.m2/repository
+          key: ${{ runner.os }}-maven-${{ hashFiles('**/pom.xml') }}
+          restore-keys: |
+            ${{ runner.os }}-maven-
+      - name: Set up JDK 1.8
+        uses: actions/setup-java@v1
+        with:
+          java-version: 1.8
+      - name: Build with Maven
+        run: mvn package --file pom.xml
+      - name: Copy artifacts
+        uses: actions/upload-artifact@master
+        with:
+          name: CommandWhitelist
+          path: target/CommandWhitelist*.jar