Keep fluentdwinsvc commandline option during upgrading

[kenhys]

Problem

When upgrading fluent-package on windows, fluentdwinsvc configuration is always reset to factory default.

Expected

If user was configured fluentdwinsvc configuration, it is better to keep it.

[daipom]

Note

• #601

Related to this, when we enable automatic service start, it is disabled again after updating.

Example(Fluent Package Command Prompt with administrative privilege):

$ sc config fluentdwinsvc start=delayed-auto