Implement full metadata row processing for search

- Added SearchResultProcessor interface to Index, which has one method -
  process - that accepts a Map<String, String> that represents a single
  metadata row returned in a search.
- Add override method for search in Index, accepting a
  SearchResultProcessor
- Implement override in FusionIndex
- Change indexTool search function to exercise the above
Merge pull request #328 from parker-ldc/github-311

Implement full metadata row processing for search
Index.SearchResultProcessor#process returns a boolean