Add github actions (#146)

Add github actions for CI

Author: echarles

.github/workflows/main.yml

@@ -0,0 +1,39 @@
+name: CI
+on:
+  push:
+    branches: 
+    - master
+  pull_request:
+    branches: '*'
+jobs:
+  build:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        python-version: [ '3.6', '3.7', '3.8' ]
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v1
+    - name: Install Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v1
+      with:
+        python-version: ${{ matrix.python-version }}
+        architecture: 'x64'
+    - name: Install the Python dependencies
+      run: |
+        pip install -e .[test]
+    - name: Install the Python dependencies
+      run: |
+        jupyter kernelspec list
+        symlinks=$(find . -type l| grep -v './git-hooks')
+        if [[ $(echo $symlinks) ]]; then
+          echo "Repository contains symlinks which won't work on windows:"
+          echo $symlinks
+          echo ""
+          false
+        else
+          true
+        fi
+        nosetests -v jupyter_server