Add initial Appveyor CI testing starting with "status" script.

appveyor.yml

@@ -0,0 +1,19 @@
+environment:
+  matrix:
+    - SCRIPT: ci_boost_status
+
+init:
+  - cd %APPVEYOR_BUILD_FOLDER%/..
+  - appveyor DownloadFile "https://raw.githubusercontent.com/boostorg/release-tools/develop/ci_boost_common.py"
+  - appveyor DownloadFile "https://raw.githubusercontent.com/boostorg/release-tools/develop/%SCRIPT%.py"
+  - cd %APPVEYOR_BUILD_FOLDER%
+install: python ../%SCRIPT%.py install
+before_build: python ../%SCRIPT%.py before_build
+build_script: python ../%SCRIPT%.py build_script
+after_build: python ../%SCRIPT%.py after_build
+before_test: python ../%SCRIPT%.py before_test
+test_script: python ../%SCRIPT%.py test_script
+after_test: python ../%SCRIPT%.py after_test
+on_success: python ../%SCRIPT%.py on_success
+on_failure: python ../%SCRIPT%.py on_failure
+on_finish: python ../%SCRIPT%.py on_finish