Add appveyor config for eventual Windows CI testing.

appveyor.yml

@@ -0,0 +1,34 @@
+environment:
+  matrix:
+    - TARGET: i686-pc-windows-gnu
+      CHANNEL: nightly
+    - TARGET: i686-pc-windows-msvc
+      CHANNEL: nightly
+    - TARGET: x86_64-pc-windows-gnu
+      CHANNEL: nightly
+    - TARGET: x86_64-pc-windows-msvc
+      CHANNEL: nightly
+
+# Install Rust and Cargo
+install:
+  - curl -sSf -o rustup-init.exe https://win.rustup.rs
+  - rustup-init.exe --default-host %TARGET% --default-toolchain %CHANNEL% -y
+  - set PATH=%PATH%;C:\Users\appveyor\.cargo\bin
+  - rustc -Vv
+  - cargo -V
+
+# Disable Appveyor's build stage. This prevents the "directory does not contain
+# a project or solution file" error
+build: false
+
+# Equivalent to Travis' `script` phase
+test_script:
+  - sh "./scripts/test.sh"
+
+branches:
+  only:
+    - master
+    # IMPORTANT Regex to match tags. Required, or appveyor may not trigger
+    # deploys when a new tag is pushed. This regex matches semantic versions
+    # like v1.2.3-rc4+2016.02.22
+    - /^v\d+\.\d+\.\d+.*$/