Change log level for internal messages to debug

[alfredbez]

The console outputs some stuff which is only needed while debugging:

$ php vendor/bin/oxid -vv | head
OXID project root is found at /var/www/oxideshop
Loading OXID bootstrap...
OXID bootstrap done
collecting comands...
commands collected
commands added

This adds to much noise imho.

My use-case: We have a cronjob, that has some info-level output, which is redirected into a log file /var/www/oxideshop/vendor/bin/oxid mycommand -vv >> /tmp/cronjoboutput.txt

With this PR, the output will only be printed when using -vvv which is the debug level.