Fix for Issue #1729. Allowed for blank first item for first two lines.

**Issue**: #1729 

**Description**:  The format for uploading a spreadsheet CSV requires the string `""` as the first entry of the first two lines.

**Fix**: Essentially, `grade_entry_item.rb` was altered to remove the check that raises an error if the header is not compatible. Instead, the `names` and `totals` arrays are shifted forward by one (to simply ignore the first csv value for the first two rows). Additionally, the language files were edited to tell users that the first item for the first two lines of the csv file could be blank. This was done in all available languages.

**Testing**: Several csv files were tested on the spreadsheet uploader to check and see if this item is ignored. The check worked for blank, `""`, and non-blank columns. Each csv file was successfully uploaded and parsed.