Soda-spark

- Add example to README about returning spark data frames as scan result

- Provides the ability to get the scan results in Dataframes. ([99](https://github.com/sodadata/soda-spark/pull/99))
- measurements
- test_results
- scan_errors
- Use version range for `soda-spark-sql` dependency
- Add `host` and `port` attributes to `_SparkDialect`

Contributors:
- [Anil Kulkarni](https://github.com/anilkulkarni87) ([#99](https://github.com/sodadata/soda-spark/pull/99))

- Fix samples not working

- Test and document sql metrics

- Add option to connect with Soda cloud

- Update documentation:
- Add example for executing a scan with file
- Explain how the `soda-spark` works
- Add change log