kiwix-serve must exit with an error after reporting an unrecognized option

[veloman-yunkan]

kiwix-serve reports unrecognized options but otherwise ignores them. This can be a problem when an option is mistyped:

$ # The correct option name is --monitorLibrary with L capitalized
$ # Below command will NOT monitory the library 
$ kiwix-serve --port=8282 --library --monitorlibrary library.xml
.../kiwix-serve: unrecognized option '--monitorlibrary'
Loading the library from the following files:
	library.xml
The library was successfully loaded.
The Kiwix server is running and can be accessed in the local network at: http://localhost:8282/