Remove getQueryTime()

* VuFindSearch/Backend/Solr/Response/Json/RecordCollection.php (getQueryTime): Removed.
  ($template): Adjust template.
* VuFindSearch/Response/RecordCollectionInterface.php (getQueryTime): Removed.
Implement delete() by directive

* VuFindSearch/Backend/Solr/Connector.php (delete): Implement
  delete() by directive.
  (update): New method. Send document to update request handler.
* VuFindSearch/Backend/Solr/Backend.php (delete): Modify function
  signature of delete() operation.
Remove WritableBackendInterface

* VuFindSearch/Backend/Solr/Backend.php: Remove
  WritableBackendInterface.
* VuFindSearch/Backend/Feature/WritableBackendInterface.php:
  Removed.
Remove Search/Listener/ListenerInterface
Fixed broken test.
Coerce optional params argument to not be null

* VuFindSearch/Service.php (search, retrieve, similar): Coerce
  optional params argument to not be null.
Fixed another broken test by setting up search service.
Hooked VuFindSearch tests into VuFind test suite.
Merge branch 'search-refactor' of ssh://vufind.git.sourceforge.net/gitroot/vufind/vufind into search-refactor
Resolving VUFIND-764.
Merge branch 'master' into search-refactor
Merge branch 'search-refactor' of ssh://vufind.git.sourceforge.net/gitroot/vufind/vufind into search-refactor