Update and rename blank.yml to CI.yml

Author: egil

.github/workflows/CI.yml

@@ -0,0 +1,20 @@
+name: CI
+
+on:
+  push:
+    branches:
+    - master
+
+jobs:
+  build:
+    runs-on: ubuntu-latest    
+    steps:
+    - uses: actions/checkout@v1
+    - name: Setup .NET core
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: 3.0.100
+    - name: Build with dotnet
+      run: dotnet build --configuration Release      
+    - name: Run unit tests
+      run: dotnet test