fix rubric_available? bug from rebase in assignment buttons
fix rubric_available? bug from rebase in assignment buttons

mkoon/gradecraft-development,mkoon/gradecraft-development,UM-USElab/gradecraft-development,UM-USElab/gradecraft-development,UM-USElab/gradecraft-development,mkoon/gradecraft-development,UM-USElab/gradecraft-development