Add test configuration for Appveyor.

.appveyor.yml

+# Windows Build Configuration for AppVeyor
+# http://www.appveyor.com/docs/appveyor-yml
+
+# build version format
+version: "{build}"
+
+os: Visual Studio 2013
+
+platform:
+  - Any CPU
+
+configuration:
+  - Debug
+  - Release
+
+branches:
+  only:
+    - master
+
+clone_depth: 5
+
+matrix:
+  fast_finish: true # Show final status immediately if a test fails.
+
+# scripts that run after cloning repository
+install:
+  - git clone https://github.com/google/googletest.git External/googletest
+
+build:
+  parallel: true  # enable MSBuild parallel builds
+  verbosity: minimal
+
+build_script:
+  - mkdir build && cd build
+  - cmake .. -DCMAKE_INSTALL_PREFIX=install
+  - cmake --build . --config %CONFIGURATION% --target install
+
+test_script:
+  - ctest -C %CONFIGURATION% --output-on-failure
+  - cd ../Test && bash runtests