Introduce ability to generate and save datasets out of the dataset definition queries mUzima Core module

This feature will maintain a table named muzima_report_dataset, which shall store dataset definition Id, results (JSON formatted), and other regular OpenMRS fields.

The feature will include a scheduler task to run the dataset definitions, and a REST resource to avail the datasets to the mobile app.

The feature shall maintain one record for each dataset definition. (i.e the results will be updated every time the query is run, and not introduce an extra row)