Fixed bug where user could not modify grades after moving through pages
Made comments more helpful for modified file
fixed a bug occuring in beta where moving between grade boxes after entering a grade would raise an alert
Merge pull request #1397 from davidrd/issue-1343

Closes #1343 - Showstopper bug in the marks spreadsheet
Merge branch 'master' of git://github.com/MarkUsProject/Markus