* save dashboard using uid rather than dashboard name

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.

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>

* refactoring to use positional statements

* refactored, realized argparse is being used in individual commands...
* added backup Makefile
* removed backup_grafana.sh and restore_grafana.sh
* removed docker_entry.sh
* (Need to update README and CHANGELOG...)
* (Need to add support for --verbose)

2) Fixed import statements - don't use `from x import *`, but import only what is needed.
2) Reformatted the code.

Continue working on PR#25 (https://github.com/ysde/grafana-backup-tool/pull/25):
* move all python into src/
* delete boilerplate restore_SOMETHING.sh scripts
* update README.md
* add some things to .gitignore

1.Make it python2 and python3 compatible 2.Try to solve special character when saving dashboard, folder problem 3.Add more verbose log message

Folders are available since Grafana v.5.0.*. Create scripts to migrate
folders and dashboards (with folders id)

* Use the PEP 8 recommended whitespace formatting for .py files
* Add intellij files to the .gitignore file patterns