* ensure compat with hide_version Grafana setting

* save dashboard using uid rather than dashboard name

* bump version
* update CHANGELOG

Update for issue https://github.com/ysde/grafana-backup-tool/issues/106

add option backup_file_format in config

fix issue of https://github.com/ysde/grafana-backup-tool/issues/96

This can make it easier to see changes when the backups are compared within version control.

Note, this changes to always pretty-print the JSON.  You might prefer that it's a configurable option.

fix typo

- #83 Fix tarfile options for python2
- #64 Remove empty folders when backup file (.tar.gz) created.

Change x:gz to w:gz for supporting python2

* added config example

This commit introduces the settings option client_cert. It is now
possible to add a file path to a client certificate in the configuration
file or as an environment variable. The default is None.

* **config file:**

```
{
  "general": {
    ...
    "client_cert": "/home/user/.certs/grafana.pem"
  },
  ...
}
```

* **env variable:** CLIENT_CERT

Signed-off-by: Jürgen Löhel <juergen.loehel@inlyse.com>

The folders.txt file previously only contained one folder, even if more than one folder was backed up.