Add sftp support

[GRbit]

changes for adapting ssh/sftp fron netangels

1. Change db_init.py to save sftp_connection info
2. Changed initSession and initCallback to work with sftp sessions
3. Add paramiko to requirements
4. Add sftp_controller (cosmetic changes in other controllers)
5. Add baseWorkerSsh (changed MainWorkerCustomer)
6. Add lib/SSH and lib/FileManager/SSHConnection
7. Reworkerd BaseWorkerSsh
   BaseWorkerSsh =>
   BaseWorkerCustomer
   + lib/SSH/sftp
   + lib/SSH/ssh
   + lib/FileManager/SFTPConnection.py
8. Add methods for copy between sftp and local/ftp

Other changes:
1. Slightly rework controllers. Now all the techniques that are used in the controller are in their respective folders
2. Add progress_helper to local and ftp workers
3. Remove sodomy in workers/local/createCopy.py
4. Add get_archive_type() in workers/local/createArchive.py