Remove beta notice from the API keys section

Upgrade mailer dependency (plausible#899)

* Upgrade mailer dependency

* Changelog

Merge pull request plausible#655 from jonnitto/patch-1

Fix: Re-add hash and outbound-links only options

Do not allow duplicate spike notification to be created

Self hosted improvements (plausible#603)

* Introduce SELFHOST config. Enable cron by default for self hosters

* Fix cron, disable custom domain for selfhost

* Add github links

* Add notice about google search console on self hosted

* Enfore BASE_URL

* Set all selfhost users' trial expiry to 100 years from now

* Fix admin user creation

Revert change to Dockerfile

Download updated user-agent files

Closes plausible#309

Release selfhosted (plausible#341)

* Optimize Dockerfile

* Update selfhosting documentation

* Remove unnecessary files

* Remove internal config stuff

* Update config

* WIP

* Use BASE_URL instead of HOST and SCHEME

* Add port to endpoint url config

* Make config/config.exs on par with config/releases.exs

* Add changelog entry

* Document configuration change