[#APOLLO-2889] Added description field to tasks.
Merge branch 'master' into APOLLO-813_Add_task_description
APOLLO-2070 Type had to be plugged back in for datetime to string coversion
Merge pull request #43 from ministryofjustice/APOLLO-813_Add_task_description

[#APOLLO-2889] Added description field to tasks.
APOLLO-2070 Updated caseItem, seems having the discriminator map one level higher does not play nice
Merge branch 'master' into APOLLO-2070
APOLLO-2070 Removed Type annotation from new field