Create ability to load historical data into mUzima forms

There's need to enable accessing historical data (Observations & Encounters) from within forms. Use cases for this feature include:

• Creating skip logic in forms based on historical data
• Trigger reminders in forms based on historical data

This shall be achieved by introducing a javascript interface that enables searching Observations using concept ID and encounters using encounter ID.

This ticket might require design discussion so as to think through possible scenarios for a comprehensive solution.