On windows Xp and maybe others wmic hangs
Update winser
Some improvements.

 - Code refactoring.
 - NSSM updated to 2.23.
 - Added more options.
fised some typos and bugs. Don't try to stop not running service when remove it.
typo
Version bump
Set async version
Merge pull request #24 from PSyton/master

Code redesign. Now it use async instead sequence.
Added check for admin rights.
Added handling service custom display name and description.
Now it's possible to set environment variables for service.
It's possible to set startup type for service.
Nssm updated to latest version.