Add OSInfo and VolumeInfo classes; generalize DatabaseUtils

• Add new OSInfo class with OSInfoTest unit test class
• Add new VolumeInfo class with VolumeInfoTest unit test class
• DatabaseUtils:
  • Switch from hardcoded Oracle driver to drivers specified via ServiceLoader provider config file
  • Enable update() method to indicate no records updated (count = -1)
  • Return -1 from getInt() if no records were found
  • Remove references to Oracle
  • Replace QueryCreds with plain ol' query string
  • Change result type of getEnum() to bounded generic
• Add DatabaseUtilsTest unit test class implemented using Derby
• Disable Sonar warnings
• Clean up .gitignore