Add an Agent Check for getting the state of Windows services.

The check will submit a metric tagged by service name that has a value
depending on the state of the service. We could extend this check to
provide more information later on.
Use Service check values and use service checks
Change Var name and remove sq brackets
Remove tags add host name
Add hostname to tags
Missing Else Statement
Remove hash for password
Merge pull request #1225 from DataDog/conor/windows_services

Conor/windows services