Switch from Travis/AppVeyor to Github Actions

Author: alexcrichton

.appveyor.yml

@@ -0,0 +1,32 @@
+name: CI
+on: [push, pull_request]
+
+jobs:
+  test:
+    name: Test
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ubuntu-latest, windows-latest]
+    steps:
+    - uses: actions/checkout@master
+    - name: Install Rust (rustup)
+      run: rustup update nightly --no-self-update && rustup default nightly
+      if: matrix.os != 'macos-latest'
+      shell: bash
+    - name: Install Rust (macos)
+      run: |
+        curl https://sh.rustup.rs | sh -s -- -y
+        echo ::add-path::$HOME/.cargo/bin
+      if: matrix.os == 'macos-latest'
+    - run: cargo test --all
+    - run: cargo test --all -- --ignored
+
+  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