Use %APPDATA% for .vuerc and other configuration files on Windows

[yanoryuichi]

What problem does this feature solve?

Make %USERPROFILE% ($HOME) clean. On Windows, configuration files should be stored in %APPDATA% instead of %USERPROFILE%.

What does the proposed API look like?

As you fixed the $XDG_CONFIG_HOME issue on Linux at #1325, please consider to use %APPDATA% on Windows.

• XDG_CONFIG_HOME: Use XDG_CONFIG_HOME for the .vuerc file #1325
• %APPDATA%: https://en.wikipedia.org/wiki/Environment_variable#Examples
• Sample: https://stackoverflow.com/questions/3250164/loading-a-config-file-from-operation-system-independent-place-in-python/3250952#3250952