Fixes string conversion bug + collect broadcast metrics

v0.1.11...v0.1.13

Somehow this repo got the tag v0.1.12, but not part of a release, hence the jump from v0.1.11 to v0.1.13.

• Collects broadcast packet metrics (#22)
• Renames metrics.yaml to metrics.yaml.sample (#23)
• Fixes an interface type conversion bug (#24)