v0.21.0

• Bump github.com/miekg/dns from 1.1.49 to 1.1.50 by @dependabot in #84
• Logger logfile: some logs added to debug the postrotate command
• Bump go-logger from v0.1.0 to v0.2.0
• Quiet text and Tls support for powerdns collector
• Documentations updated
• Major code factory and new config file