Merge #227

227: Implement simple SMTP handler r=mkmik a=mkmik

Closes #215

This PR implements a SMTP client (supporting auth, TLS etc).

```
$ kubewatch  config  add smtp
CLI setters not implemented yet, please edit ~/.kubewatch.yaml directly. Example:

handler:
  smtp:
    to: "myteam@mycompany.com"
    from: "kubewatch@mycluster.com"
    smarthost: smtp.mycompany.com:2525
    subject: Test notification
    auth:
      username: myusername
      password: mypassword
    requireTLS: true
```

TODO: template the subject based on the event metadata/actions.

Co-authored-by: Marko Mikulicic <mkmik@vmware.com>
Co-authored-by: Marko Mikulicic <mkm@bitnami.com>

Merge pull request #108 from nabadger/feat-watch-ingress

Add support for monitoring ingress events.

Merge pull request #61 from ngtuna/refactor-watcher

Refactor watcher

Merge pull request #55 from ngtuna/config-path

revert config path to `$HOME`