WRLC-32: Implement a generic Islandora explore block in islandora solr...

...search module.
Think this check is too generic. This will fire on ever block configuration call so it's possible there'll be another module that has a block with a value of `explore`. 

Looking at a dsm of `$form`, we could probably check `$form['module']['#value'] == 'islandora_solr'` and the check above will still be valid.