Make .travis.yml and .appveyor.yml work, rename appveyor.yml

The appveyor script can not use a single quoted double quotes string,
like '"C:\Spaces are trouble\"', hence the solution of defining an
environment variable.

appveyor.yml has been renamed to .appveyor.yml to keep consistent with
.travis.yml and to be default hidden.

.appveyor.yml

@@ -0,0 +1,28 @@
+image: Visual Studio 2017
+
+environment:
+  matrix:
+  - QT_LOC: '"C:\Qt\5.11.2\msvc2017_64\bin\"'
+    VS_LOC: '"C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\VC\Auxiliary\Build\vcvarsall.bat"'
+    JOM_LOC: '"C:\Qt\Tools\QtCreator\bin\jom.exe"'
+    NSIS_LOC: '"C:\Program Files (x86)\NSIS\"'
+    ZIP_LOC: 7z
+    CLANG_FORMAT_LOC: '"C:\Program Files\LLVM\bin\clang-format.exe"'
+    COMPILER: msvc
+    VSVER: 14
+    
+
+clone_depth: 1
+
+init:
+  - set TAG_NAME=%APPVEYOR_REPO_TAG_NAME%
+
+build_script:
+  - python ./build_scripts/run-clang-format.py ./src -r --clang-format-executable %CLANG_FORMAT_LOC%  --color always
+  - call "build_windows.cmd"
+
+artifacts:
+  - path: bin\win64\AdvancedSettings.zip
+    name: portable
+  - path: installer\AdvancedSettings-Installer.exe
+    name: installer