Add Header row configuration option

[jhill0]

This configuration will allow csv's to have the header on a line other than the first line of the csv, useful for skipping data not relevant to midpoint. The header row configuration option is expecting an int and defaults to the first row to maintain backward's compatibility.

[1azyman]

Thank you for PR.

Before merging this feature, can you please implement at least one test, which will read such csv file and create/update one row there?
I guess that validation should be added for new configuration property as well. What happens if user will put there number < 1? I guess validation should throw configuration exception.