Removed patient_id arrays from Carer

+ Fixed some mine faults with refreshing the patient list after adding
a new

Patient has 1 carer and if a new carer adds patient then the patient
only has the new one
Merge pull request #33 from knotsoftware/activities

Activities model, end point api, tests implemented. View implemented with table sorting and filtering
Merge pull request #34 from knotsoftware/remove-other-carer

Removed patient_id arrays from Carer
Added more functionality to the activities tab including the addition of the enum functionality