Integrate SearchEngine

[kenprice]

Completed @jkarner 's jillian-feature-testworkflow branch.

Follows this diagram for the most part, sans error handling. But we'd like to make a PR so we can move on to integration testing.

PR should:

• Have handle_request for SearchEngine return a SearchResult given a SearchRequest.
  • Call tagger's tagger_service if document is provided
  • Call geocoder's get_locations if coordinates are provided
  • Collate outputs of these components into array of SearchTerm, and add any additional user-provided search terms to the array.
  • Use this array of SearchTerm to dispatch a query to SolrSearch.
• Change spec of Providers\SolrSearch and Services\Search to have query return SearchResultItem[] instead of SearchResult.
• Normalize fields for search results return by SolrSearch (bug fix).
• Add additional tests for SearchEngine.

[kenprice]

@rraub Failing due to decreased test coverage; is the current coverage acceptable?