Update search to better align with REST API

REST API returns JSON Serialized List<SObject>, current RemoteTK
controller serializes List<List<SObject>>, which is the default return
of a SOSL query - this better aligns the RemoteTK implementation with
the ForceTK REST API implementation for better interoperability and
interchangability.

Iterate the List of List<SObject> and merge with addAll.