Review Maven plugin logging

[sdeleuze]

It seems also that System.out.println are not working anymore in ConfigOptions after the switch to bti, so we should maybe use a logger to get the relevant output like for System.out.println("Spring Native operating in "+MODE+" mode");.

[aclement]

All the existing verbose logging with spring.native.verbose was converted to proper Java logging. I'll change the remaining few sysouts under this bug. You can turn on verbose mode by using the standard maven -X option which turns on debug logging for a run (you will see everything that previously came out in verbose mode).

[sdeleuze]

I reopen it to review logging once #484 will be fixed since I can't see logs for example Spring Native operating in ... mode which was displayed without having to set spring.native.verbose. I think we should avoid requiring having to set -X, -e should be enough.

[sdeleuze]

With 78f792c it seems to work properly, I have configured Spring Native operating in ... mode to logged at info level.