moby: Block new unsupported docker commands on Windows

Trying the latest rc binaries on Windows Server 2016 TP5 leads to errors that lead to the assumption that new function could work. It would be better to block these commands on Windows with a better error message.

Output of docker version:

Client:
 Version:      1.12.0-rc1
 API version:  1.24
 Go version:   go1.6.2
 Git commit:   1f136c1
 Built:        Wed Jun 15 04:49:14 2016
 OS/Arch:      windows/amd64

Server:
 Version:      1.12.0-rc1
 API version:  1.24
 Go version:   go1.6.2
 Git commit:   1f136c1
 Built:        Wed Jun 15 04:49:14 2016
 OS/Arch:      windows/amd64

Output of docker info:

Containers: 9
 Running: 0
 Paused: 0
 Stopped: 9
Images: 30
Server Version: 1.12.0-rc1
Storage Driver: windowsfilter
 Windows:
Logging Driver: json-file
Plugins:
 Volume: local
 Network: nat null overlay
Swarm: inactive
Kernel Version: 10.0 14300 (14300.1030.amd64fre.rs1_release_svc.160603-1734)
Operating System: Windows Server 2016 Datacenter Technical Preview 5
OSType: windows
Architecture: x86_64
CPUs: 2
Total Memory: 4 GiB
Name: vagrant-2016
ID: QIHN:JA6P:4W5I:ASMZ:2P5G:3VU3:ILQZ:MTN4:ONGA:BOC7:JBRI:N3NB
Docker Root Dir: C:\ProgramData\docker
Debug Mode (client): false
Debug Mode (server): false
Username: stefanscherer
Registry: https://index.docker.io/v1/
Insecure Registries:
 127.0.0.0/8

Additional environment details (AWS, VirtualBox, physical, etc.):

Windows Server 2016 TP5

Steps to reproduce the issue: 1. 2. 3.

Describe the results you received:

C:\> docker swarm init
Error response from daemon: remove C:\ProgramData\docker\swarm\worker\tasks.db: The process
cannot access the file because it is being used by another process.

Describe the results you expected:

Command swarm is not supported on Windows