Adds drop-down select to filter networks by VPC.
-If no VPC is selected, only show non-VPC isolated networks
-If VPC is selected, show tiers from specified VPC. Note that only one
tier/network can be checked at a time in this mode, and 'add network'
text field is hidden
** Note: this is a work-in-progress, and only contains dummy content
Implement UI for managing VPC tiers, via a custom chart-like UI list
tiers and allowing the management of VMs associated with the VPCs.