#712 Advanced build matrix [skip travis]

Signed-off-by: Uilian Ries <uilianries@gmail.com>

appveyor.yml

@@ -481,15 +481,15 @@ for:
     matrix:
       only:
         - configuration: Debug
-      - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-        CONAN_VISUAL_VERSIONS: 12
-        PYTHON: "C:\\Python37"
-      - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
-        CONAN_VISUAL_VERSIONS: 14
-        PYTHON: "C:\\Python37"
-      - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
-        CONAN_VISUAL_VERSIONS: 15
-        PYTHON: "C:\\Python37"
+        - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+          CONAN_VISUAL_VERSIONS: 12
+          PYTHON: "C:\\Python37"
+        - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+          CONAN_VISUAL_VERSIONS: 14
+          PYTHON: "C:\\Python37"
+        - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+          CONAN_VISUAL_VERSIONS: 15
+          PYTHON: "C:\\Python37"
     install:
       - set PATH=%PATH%;%PYTHON%/Scripts/
       - pip.exe install conan conan_package_tools