Improve user experience on mUzima app landing page when list is long

Whenever the user navigates to the landing page (e.g after logging in), the app attempts to load the full list of patients. In case the list is long (e.g if the device has 2000 patients), the app takes long before the user can select and navigate to the patient summary for one patient. During the wait time, the app does not respond to user clicks/taps for selecting a patient.

There's a need to improve the algorithm that loads patients (e.g display a few, then load more upon user scrolling)