GlideAggregate

1. Instantiate GlideAggregate object, include table in parameter.
2. addQuery method will restrict returned data-set based on added queries.
3. addAggregate groups the returned data-set by second argument within parameters & the first argument within the parameters is the calulation ran based on that grouping.
4. query runs glideaggregate.
5. getAggregate collects the data-set grouped by data.