And per Alex's request, add default value directly into the database, rather
than using it at last minute of implemention.
status 13829: resolved fixed
Reviewed-by: Alex
-made Netscaler, SRX, F5 network elements as pluggable service
-added abstract load balancer device manager ExternaLoadBalancerDeviceManager
-made both F5 and Netscaler pluggable service to extend ExternaLoadBalancerDeviceManager
-added abstract firewall device manager ExternalFirewallDeviceManager
-made SRX pluugable service to extende ExternalFirewallDeviceManager
-added API's to configure and manage netscaler devices