added save corpus field details
for #1777 making datum fields reorderable by default
for #1777 adding an empty datum field if users wnat mroe fields
Removing all customized tempaltes from the spreadsheet app

since we can now customize the fields per corpus, they are no longer needed. instructors can set their own fields, reordr htem, set as many columns as they want and if they want no-olumnar layouts THEN we can customize the lay out for them using html.

for #1615 #9 #391 #1777 #1659  #1645 #1626 #1650 #1625 #1773 #1302  #1419 #1290 #1544 #1291 #1615 #1387 #1283 #1073
Merge pull request #1781 from cesine/master

Reorder and create new corpus fields