Add Zulip alerting

Closes privatestorageops#455

See merge request !389

Thanks @bendon!

.. that I forgot earlier.

Increase load15 alert to only fire if it's over 1 for 2 hours or more

See merge request !388

Recently this alarm fired a couple of times when the backup self-
check ran.

Set it to alert only when load is over 1 for longer than 2 hours.

Crank up borgbackup log level to INFO (from default WARN)

Closes #136

See merge request !385

Rotate my SSH key for the testing grid

See merge request !386

The default log level ("WARN") means borgbackup does not output
anything (and exits with a "0" return code) on success.

We'd like to have some more insight into long-running monthly
backup repo checks and turn up the log level to "INFO" with
this change.

See https://borgbackup.readthedocs.io/en/stable/usage/general.html#common-options .

Fixes #136.

Monitoring: Fix max CPU usage graph

See merge request !383

Add new ssh key from security token

Closes #134

See merge request !382

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Changing my key after leaking the private part!

See merge request !381

Add the dev team's SSH keys to staging

Closes #132

See merge request !377

Add public keys of Andreas and Ben to access staging

Closes #132

See merge request !375

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Signed-off-by: Benoit Donneaux <benoit@leastauthority.com>

Update readme

See merge request !373

Add our new Stripe webhook to the payment dashboard

See merge request !371

Fix the payment link creation script

Closes #131

See merge request !370

Support the new Stripe payment workflow

See merge request !368