Add Github Actions build

Signed-off-by: Gábor Lipták <[email protected]>

.github/workflows/ci.yml

@@ -0,0 +1,17 @@
+name: ci
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v2
+    - name: Build
+      run: |
+        docker build --tag gridstudio:latest grid-app/