Add some playground love (#57)

.devcontainer/Dockerfile

+FROM jeluard/substrate-playground-template-base@sha256:35683978140807d8e3c9eaa814e9034bd254e74224073984db2159302d44946b
+
+ADD . .
+
+RUN cargo build --release
\ No newline at end of file

.devcontainer/devcontainer.json

+{
+    "name": "Substrate Node template",
+    "dockerFile": "Dockerfile",
+    "settings": {
+      "terminal.integrated.shell.linux": "/bin/bash",
+      "lldb.executable": "/usr/bin/lldb"
+    },
+    "extensions": [
+      "rust-lang.rust",
+      "bungcip.better-toml",
+      "vadimcn.vscode-lldb"
+    ],
+    "forwardPorts": [
+      3000,
+      9944
+    ]
+  }
+  
\ No newline at end of file

.github/workflows/build-push-template.yml

+name: Build and Push template
+
+on:
+  push:
+    branches:
+    - master
+
+jobs:
+  build-push-template:
+    runs-on: ubuntu-18.04
+    steps:
+    - uses: actions/checkout@v2
+
+    - name: Build and push the node-template Docker image
+      uses: docker/build-push-action@v1 # https://github.com/docker/build-push-action
+      with:
+        username: ${{ secrets.DOCKER_USERNAME }}
+        password: ${{ secrets.DOCKER_PASSWORD }}
+        dockerfile: .devcontainer/Dockerfile
+        repository: jeluard/substrate-playground-template-node-template
+        tags: latest
+        add_git_labels: true
+        tag_with_ref: true
+        tag_with_sha: true
+
+    - run: echo ::set-output name=image::jeluard/substrate-playground-template-node-template:sha-${GITHUB_SHA::7}
+      id: env
+
+    - name: Update devcontainer.json
+      run: |-
+        t=$(mktemp)
+        cat .devcontainer/devcontainer.json | jq ".image = \"${{ steps.env.outputs.image }}\"" > ${t} && mv ${t} .devcontainer/devcontainer.json
+
+    - name: Commit .devcontainer.json update
+      uses: EndBug/add-and-commit@v4
+      with:
+        message: ":bookmark: update image"
+        add: ".devcontainer/devcontainer.json"
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+
+    - name: Trigger playground inclusion
+      uses: peter-evans/repository-dispatch@v1
+      with:
+        token: ${{ secrets.REPO_ACCESS_TOKEN }}
+        repository: paritytech/substrate-playground
+        event-type: template-updated
+        client-payload: '{"id": "node-template", "image": "${{ steps.env.outputs.image }}"}'
\ No newline at end of file

.vscode/tasks.json

+{
+    // See https://go.microsoft.com/fwlink/?LinkId=733558
+    // for the documentation about the tasks.json format
+    "version": "2.0.0",
+    "tasks": [
+        {
+            "label": "Run ",
+            "type": "shell",
+            "command": "cargo",
+            "args": ["run", "--release", "--", "--dev"],
+            "group": {
+                "kind": "build",
+                "isDefault": true
+            },
+            "presentation": {
+                "reveal": "always",
+                "panel": "new"
+            },
+            "problemMatcher": [
+            {
+                "owner": "rust",
+                "fileLocation": ["relative", "${workspaceRoot}"],
+                "pattern": {
+                "regexp": "^(.*):(\\d+):(\\d+):\\s+(\\d+):(\\d+)\\s+(warning|error):\\s+(.*)$",
+                "file": 1,
+                "line": 2,
+                "column": 3,
+                "endLine": 4,
+                "endColumn": 5,
+                "severity": 6,
+                "message": 7
+                }
+            }
+            ]
+        }
+    ]
+}
\ No newline at end of file

README.md

+[![Try on playground](https://img.shields.io/badge/Playground-node-templates-brightgreen?logo=Parity%20Substrate)](https://playground-staging.substrate.dev/?deploy=node-templates)
+
 # Substrate Node Template
 
 A new FRAME-based Substrate node, ready for hacking.