Adding tests around the backup tool.

o Tests covering the following:
  o Copying of files from store -> backup
  o Transactions that happen during copy are replayed
    onto the backup store
  o A transaction log contianing the latest transaction
    for lucene & neostore is in the backup
Merge pull request #1928 from mneedham/1.9-main-testing-backup

Adding tests around the backup tool.