Added
* top level flag `--log-level` to set swarmlib's verbosity ([29](https://github.com/HaaLeo/swarmlib/issues/29)). It can be one of `debug`, `info`, `warning`, `error`, `critical`. Contributed by Nikos Koutsovasilis ([nkoutsov](https://github.com/nkoutsov)) and happily accepted 🚀.
[All Changes](https://github.com/HaaLeo/swarmlib/compare/v0.11.0...v0.12.0)