Installation script for Windows

Just looking through the existing install shell script and noting these lines:

#elif [[ "$OSTYPE" == "win32" ]]; then
#        # I'm not sure this can happen.

I haven't been on Windows in a long time, but I know they do support Ubuntu shell now. I'm just not sure how well the integration fits together, so you're probably right in the assumption what we wouldn't get that $OSTYPE.

What I'm thinking is that it might be best if a PowerShell script (.ps1) was provided for installing the CLI on Windows. But, that would mean the Travis build would need to output a Windows executable.

I know you're already working on builds for other operating systems, so no rush to get an .exe built. Just letting you know I'm happy to write the .ps1 file when the time comes.

[sleipnir]

Thanks! Would be really cool to see a powershell script for windows.
For now cloudstate-cli relies heavily on native system and docker tools, kubernetes, etc. to work properly, so a Windows version is a bit more complicated than Unix like versions. However, we need to add support for Windows as soon as possible.