Switch CI to Github Actions

Author: alexcrichton

.github/workflows/main.yml

@@ -0,0 +1,42 @@
+name: CI
+on: [push, pull_request]
+
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        rust: [stable, beta, nightly]
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust
+      run: rustup update ${{ matrix.rust }} && rustup default ${{ matrix.rust }}
+    - run: cargo test
+
+  rustfmt:
+    name: Rustfmt
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust
+      run: rustup update stable && rustup default stable && rustup component add rustfmt
+    - run: cargo fmt -- --check
+
+  publish_docs:
+    name: Publish Documentation
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - name: Install Rust
+        run: rustup update stable && rustup default stable
+      - name: Build documentation
+        run: cargo doc --no-deps --all-features
+      - name: Publish documentation
+        run: |
+          cd target/doc
+          git init
+          git add .
+          git -c user.name='ci' -c user.email='ci' commit -m init
+          git push -f -q https://git:${{ secrets.github_token }}@github.com/${{ github.repository }} HEAD:gh-pages
+        if: github.event_name == 'push' && github.event.ref == 'refs/heads/master'