#102 DetectColumnCountChanges and CsvBadDataException issue when there are extra columns in some rows

- Modified how the FieldCount is set
  1. If header does not exist, then update FieldCount
  2. If header does exist and it is the first row, then update FieldCount
- Added a unit test InconsistentColumnsMultipleRowsTest()
Merge branch 'issue-102' of https://github.com/joshgo/CsvHelper into joshgo-issue-102

Conflicts:
	src/CsvHelper.Tests/CsvParserTests.cs