Added Microsoft AppInstaller Mime-Types

[shartte]

Microsoft now allows Windows 10 App packages to be distributed from Websites by using appinstaller files and simply publishing the used packages via HTTP. Sadly, the installer seems sensitive to the correct Mime-Type being sent by the Webserver, which is why they included custom Mime-Types in their setup guide. This adds those mime-types. Luckily they map 1:1 with the custom extensions used for the package files.