Add Arris DG950A SNMP data extraction module

This module will extract critical data such as WPA and WEP keys from
the Arris DG950a model cable modem via the SNMP protocal.
Update arris_dg950 module with required changes

Collapsed several levels of the if/else statement and changed out 2 with
case. Changed print_good to print_line. Removed rescue ::Interrupt and
altered variable names to make them more readable
Land #3760, Arris WEP/WPA leak from @dheiland-r7