More appropriate log levels

[lukas-krecan]

Warning usually means that something went wrong

[oridool]

@lukas-krecan - thanks for this PR.
However, I prefer to keep the log level as it is (Warning).
Most applications are running by default on log level warning. And those logs coming from this library are only written once, upon startup. I prefer seeing those to know everything was ok on startup. Changing to info level will omit those startup logs.

If you want, you can always customize the log level externally for the specific class/package by using system property (or application.yml in SpringBoot)