Add paramiko library to use SFTP from Python.
Add support for controlling backup deamon using notifier.
Add model class representing pending and finished backup.
Improve Progress component.

* Add onFinished event
* Create dedicated mode for representing pending backup progress.
Initial version of web backup interface.
Gracefully respond to ^C.

Conflicts:
	gui/tools/backup.py
Add backup/restore options to netcli.
Enlarge FlashDevice to 4GiB to fit the build.
Fix Progress component.

Now it displays single progress bar and status message obtained
from server.
Allow null values in backup worker PID field.
Remove backup button from sidebar nav and move to Advanced tab.
Many updates in backup daemon.

* Add compression support for data
* Implement abort backup using unix socket command
* Make code more bulletproof
Mark backup as failed if worker process dies.
Make changing 'Cancel' button label possible.
Web UI updates:

* Added abort feature
* Visual improvements of backup dialogs
* Added support for backup compression
Add support for key-based authentication.
Add Backup model migration.
Remove unused variable.
Minor fixes.
Sort backups by id which will help if system date/time gets changed backwards.