improve comment about log messages in solr service model
solr request process_add only looks for items matching target and sources, and raises exception if it finds more than 1
cosmetic tweak to solr_request
merge looks for items matching target, not any items;  pass id to merge_item_hashes so it can raise exception with id if no items are found
have better error message when no items found for merging records, and adjust specs
add specs to SolrDocument for id param on solr_add
ensure SolrDocument sends SolrService String for add_doc_as_xml
intermed - writing specs and refactoring merge service
added specs for merge_item_display and refactored it
refactoring merge_service and spec for readability
refactor MergeService.merge_field and get specs passing
add tests for merge service #merge_in_doc_hash and refactor code accordingly
rename merge_items (was merge_item_hashes) in merge service
added specs for merge_items and reorged a bit
added two specs for SolrRequest.process_add
finish SolrRequest.process_add specs
add log_level debug to development environment file