workbook_structure __init__()

Workbook_Structure had no provision to handle end_rows at line 636 and 641 .
change in Workbook_structure 

We count columns in excel workbook from 1. And we have been passing them in this format. But in pandas.Excelfile.parse() counts it from 0. So, it might be beneficial to abstract that conversion in the Workbook_structure class.