Tidy up some warnings and hints
Remove all traces of metadataStorageInfo.

The field is never set in SolrLogger, so getMetadataStorageInfo always
returns null.  Attempts to dereference the Map supposedly returned
should thus always terminate abruptly.
Merge pull request #464 from mwoodiupui/DS-1531

[DS-1531] bug in current DSpace (3.1) with log importing