Actions build (#340)

* Build with GitHub Actions

* Changing dotnet-version

* Updating version again

* Updating path to sln and adding test step

* Updates to file path

* Path is probably starting out at the root

* Updating path once again

* Updating name

* Adding build badge to readme

* Making the build work in markdown

.github/workflows/dotnetcore.yml

@@ -0,0 +1,19 @@
+name: eShopOnWeb Build and Test
+
+on: [push]
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+    - name: Setup .NET Core
+      uses: actions/setup-dotnet@v1
+      with:
+        dotnet-version: 3.1.100
+    - name: Build with dotnet
+      run: dotnet build ./eShopOnWeb.sln --configuration Release
+    - name: Test with dotnet
+      run: dotnet test ./eShopOnWeb.sln --configuration Release