Sync the defaults of VPNaaS forms with the server-side defaults

Also clears the unnecessary default values of remote peer subnet,
remote peer address, peer id and PSK.

Split IPSec Site connection creation form into two tabs (required
and optional parameters) since it has many parameters.

Closes-Bug: #1222255

Camel-case resource names (e.g., VPNService, IPSecPolicy...) are
replated by names with spaces like "VPN Service", "IPSec Policy"
and so on.

Change-Id: Ie0d77189ab3fc6d0722ece28abced9192ea0740b
Merge "Sync the defaults of VPNaaS forms with the server-side defaults"