Add option for Mass Download of all Device Configurations

Example URL:

o https://198.18.137.8/dashbd/configurations.php?method=downloads&all_devices=1&global=0&global_grouping=5&download_type=1&mass_download=Download+Configuration%28s%29.

o Currently, we are able to only download the backup of the Netreo system. We would also like to download and store device configurations offsite in the event of system failure.