Enable Solr query for object selection

[ctgraham]

Problem / motivation

As an administrator, if I am using Solr I prefer it for searching because I have done extra configuration work on weighting, and base filter, etc. I would like to use a Solr query in place of the RI query for object linking.

Proposed resolution

Detect the present of the Solr search module, and when present, prefer Solr to the SPARQL.

Remaining tasks

• Update "Remaining tasks"
• Write automated tests
• Code review
• Commit

User interface changes

None, or perhaps a new configuration page which optionalizes Solr use.

API changes

None.

Data model changes

None.