#957 Crypt backups files

[Anonymous]

Originally created by: r3gis...@gmail.com
Originally owned by: r3gis...@gmail.com

Backup files should be crypted on the sdcard.
While not done users should take care with apps that are authorized to access their sdcard. Or just move the backup and save it in a secure place.

Note that many other sip app even desktop does not really take care about this point (even for active config files), but CSipSimple should do ;).