Instead of hardcoding and tight coupling of relation resolving, we now
provide a dataprocessor instead.
Therefore you need to configure resolving for each indexed type.
This resolves#149 and #147.
Use own service to handle data processing. Classes like indexer should
not know anything about the structure and how to process the data.
Also rename record to data, as we can process just any data in form of
an array.
Relates: #116