Schema changes

[John Milner]

alter table benchmark_grade_mark add column description varchar(255);

alter table benchmark_grade_item change date date date;

[John Milner]

alter table sis_schoolyear add column benchmark_grade tinyint(1) not null;

alter table benchmark_grade_aggregate add column cachedValue decimal(8,2);

alter table benchmark_grade_aggregate add column singleMarkingPeriod_id int(11) default null;

alter table benchmark_grade_aggregate add key `benchmark_grade_aggregate_5f068da5` (`singleMarkingPeriod_id`);