Add appveyor for Windows CI support

appveyor.yml

@@ -0,0 +1,56 @@
+image: Visual Studio 2017
+environment:
+  global:
+    # SDK v7.0 MSVC Express 2008's SetEnv.cmd script will fail if the
+    # /E:ON and /V:ON options are not enabled in the batch script intepreter
+    # See: http://stackoverflow.com/a/13751649/163740
+    CMD_IN_ENV: "cmd /E:ON /V:ON /C .\\appveyor\\run_with_env.cmd"
+
+  matrix:
+    - PYTHON: "C:\\Miniconda37-x64"
+      PYTHON_VERSION: "3.7.0"
+      PYTHON_ARCH: "64"
+    - PYTHON: "C:\\Miniconda35-x64"
+      PYTHON_VERSION: "3.5.3"
+      PYTHON_ARCH: "64"
+    - PYTHON: "C:\\Miniconda36-x64"
+      PYTHON_VERSION: "3.6.1"
+      PYTHON_ARCH: "64"
+
+
+install:
+  # If there is a newer build queued for the same PR, cancel this one.
+  # The AppVeyor 'rollout builds' option is supposed to serve the same
+  # purpose but it is problematic because it tends to cancel builds pushed
+  # directly to master instead of just PR builds (or the converse).
+  # credits: JuliaLang developers.
+  - ps: if ($env:APPVEYOR_PULL_REQUEST_NUMBER -and $env:APPVEYOR_BUILD_NUMBER -ne ((Invoke-RestMethod `
+        https://ci.appveyor.com/api/projects/$env:APPVEYOR_ACCOUNT_NAME/$env:APPVEYOR_PROJECT_SLUG/history?recordsNumber=50).builds | `
+        Where-Object pullRequestId -eq $env:APPVEYOR_PULL_REQUEST_NUMBER)[0].buildNumber) { `
+          throw "There are newer queued builds for this pull request, failing early." }
+  # Prepend newly installed Python to the PATH of this build (this cannot be
+  # done from inside the powershell script as it would require to restart
+  # the parent CMD process).
+  - "SET PATH=%PYTHON%;%PYTHON%\\Scripts;%PATH%"
+
+  # Check that we have the expected version and architecture for Python
+  - python --version
+
+  # Because of issue #193, we have to keep pip in version 18.
+  - python -m pip install --disable-pip-version-check pip==18
+  - pip install cython
+  - pip install https://github.com/Qiskit/qiskit-terra/archive/master.zip
+  # Due to https://github.com/ContinuumIO/anaconda-issues/issues/542
+  # we need to pass --ignore-installed, otherwise Python3.5 will fail
+  # while upgrading setuptools.
+  - pip install --ignore-installed -r requirements-dev.txt
+  - python setup.py bdist_wheel -- -G "Visual Studio 15 2017 Win64"
+  - pip install --find-links=dist\ qiskit_aer
+
+
+build: off
+
+test_script:
+  # Run the project tests
+  - python -m unittest discover -s test/terra -v
+