Fixed issue where threads were being killed before they completed.
Fixed 0 byte Attachment Downloads
This was caused by the assumed user being changed while a thread was still running.
Fixed issue with downloading sheet attachments for multiple accounts.
This was caused by Objects being passed to the threads and were being altered by each thread.
- Added cloning ability to Smartsheet Services
- Cloned objects for each thread
Set download timeout to Integer.MaxValue and cleanup of message to user.
Merge branch 'master' of github.com:smartsheet-platform/backup-java
 - Fixed issue where some files were downloading with a file size of 0 bytes.
 - Changed default download timeout to over 24 hours.
 - Files are now backed up to a timestamped sub-folder in the backup directory
 - Better error handling when a file or attachment is deleted while the backup is running.
 - Added a user agent to API requests.