This is the basic code to add the Windows Service Manager hooks to Nomad.
Includes vendoring golang.org/x/sys/windows/svc and added Docs:
* guide for installing as a windows service.
* configuration for logging to file from PR #6429
* vendor: bump libcontainer and docker to remove Sirupsen imports
* vendor: fix bad vendoring of archive package
* vendor: fix api changes to cgroups in executor
* vendor: fix docker api changes
* vendor: update github.com/Azure/go-ansiterm to use non capitalized logrus import
