UI plugins: Fix side nav behavior

Due to usability issues, any UI plugins that add a main section (via the
addSection function) will now be shown in the 'Plugins' area by clicking
on the relevant tile. This is to prevent overflow of the side nav bar
caused by too many plugins being loaded.
CLOUDSTACK-730: UI > VPC > Router > site-to-site VPN > VPN Connection > Create VPN Connection - add new checkbox "passive", default it as unchecked.