Sendria

* auth mechanisms are now implemented in [aiosmtpd](https://aiosmtpd.readthedocs.io)
(thanks [Arzaroth](https://github.com/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](https://github.com/KathrynN) for reporting)
* fixed API response when there is no data to return (3) (
thanks [KathrynN](https://github.com/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

* complete rewrite of backend part. MailTrap is using [asyncio](https://docs.python.org/3/library/asyncio.html) and [aio-libs](https://github.com/aio-libs/) now:
* switch to [aiohttp](https://docs.aiohttp.org/) from Flask
* switch to [aiosmtpd](https://aiosmtpd.readthedocs.io) from [smtpd](https://docs.python.org/3/library/smtpd.html)
* switch to [aiosqlite](https://github.com/omnilib/aiosqlite) from [sqlite3](https://docs.python.org/3/library/sqlite3.html)
* changed logger to [structlog](https://www.structlog.org/)
* using asynchronous version of libraries drastically improved performance
* `MailTrap` now can send a webhook about every received message
* show in GUI information about envelope sender and recipients
* all API requests has their own namespace now: `/api`
* allow to replace name of application or url in template
* block truncating all messages from GUI (on demand)
* fixed issues with `WebSockets`, should refresh mails list and reconnect if disconnected
* fixed issues with autobuilding assets
* many cleanups and reformatting code
* addons for [nginx](https://github.com/msztolcman/mailtrap/tree/master/addons/nginx.conf) and [supervisor](https://github.com/msztolcman/mailtrap/tree/master/addons/supervisor.conf)