Better logs, better inserts

• auth mechanisms are now implemented in aiosmtpd
  (thanks Arzaroth for PR)
• huge improvements to handling DB inserts. Now all messages are stored in an internal queue,
  then it's saved to the DB. It solves many problems with performance and single-threaded
  SQLite (thanks KathrynN for reporting)
• fixed API response when there is no data to return (#3) (
  thanks KathrynN for reporting)
• improved logging system, now log messages has log levels, also many simplifications in
  logging system
• Sendria now introduce as itself when connect through SMTP (also --smtp-ident CLI param added)
• minor fixes and performance issues solved, updated dependencies
• next step in cleanups and making code modern