Add section info to import / export

passed QA for gradebook version 1.5.0-b4

QA Test
on smartsite-dev server
site: DLW Test BIS 010V A01-A06 SQ 2010
with multiple sections

set to display the section column
entered grades in Gradebook2 tool spreadsheet.
exported grades and structure
exported grades only
set Gradebook2 to not display the section column
exported grades and structure
exported grades only
compared the pairs (grade and structure, grades only) of export files created with and without the section displayed – no differences found
added grades in one of the grades only file created when the section hidden, and imported the file – the grades came in correctly, the section column info was not displayed during import process.
the imported grades appeared in the gradebook
imported the grades and structure file (unmodified) that was created when the section information was displayed – the blanks came in correctly, the section column info was not displayed during the import process.
the imported blanks replaced the previously imported grades.

QA Pass

r73989

I have tested output, and bringing in both new and old files on top of each other. There's one problem which relates to an NPE (), but as it works if the names are different there's no reason to assume it will not work once is fixed.

Implementing this in relation to the current import/export process.

Estimate: 1 SP