- #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

removed s3 from default config

* added config example

fix a couple of typos

fixed issue #77 TypeError: health_check

require api checks to succeed before save or restore

Introduces the settings option client_cert

Fixed Bug folders.txt does not contain all folders

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.

initial s3 support

update README.md to include pypi installation

add long_description_content_type='text/markdown' in setup.py, so that this project can be uploaded to pypi

Fix parameters for get_folder_id_from_old_folder_url

Refactored as PyPi compatible package 

* Remove ability to use yaml for configuration in favor of json
* Remove conf module
* README.me updates

* replaced pathlib with os.path
* added JSON config support