Allow service editing on the command line.

Individual service parameters can now be queried or edited on the
command line.  The syntax is designed to be intuitive and is
described in some detail in the README.  Some examples follow:

    nssm get Selenium Application

    nssm get "My Batch Job" AppExit 0

    nssm get Jenkins AppEnvironmentExtra CLASSPATH

    nssm get Netlogon ImagePath

    nssm set UT2004 Application C:\Games\UT2004\System\UCC.exe

    nssm set UT2004 AppParameters server

    nssm set UT2004 AppExit Default Exit

    nssm set Jenkins ObjectName DOMAIN\ci correct horse battery staple

    nssm set "My Batch Job" AppExit 0 Exit

    nssm set WowzaMediaServer362 Start SERVICE_DELAYED_START

    nssm set UT2004 Type SERVICE_INTERACTIVE_PROCESS

    nssm reset UT2004 AppEnvironment

    nssm reset UT2004 ObjectName