Add posibility to make the backup file password protected

Add posibility to make backup file password protected
1. Go to Poulpe -> Components -> Components -> Admin Panel
2. Right click Admin Panel and select Backup Database

AR:
The file.gz is created and downloaded to user's computer
The file can be read by any user from this computer etc.

ER:
Admin has possibility to define password before backup
or even admin is forced to define password - backup will not be created without it