Merged latest changes from http://github.com/jhuckabee/drupal-exhibit (9399803) by jhuckabee.

Changelog (Exhibit):
- Allow user to specify Exhibit extension paths.
- Grab the Map API key from GMap/Keys module if available.
- Default the Exhibit definition to the most basic Exhibit.
- Added a reference to the new calendar extension.
- Fixed CCK date rendering for multi-value dates.

Changelog (Exhibit ApacheSolr):
- Implemented an ApacheSolr integration module.