Fix logic for VPN badges and network menu order

Fix logic for VPN badges and network menu order

There were a few bugs, and some confusing UI. I made the following changes:
* Moved the ShouldShowIconInTray() logic into NetworkMenuIcon.
* Removed the unused function GetVpnImage()
* Made VPN icon code similar to other network types
* Changed network display order to:
** Active network
** Connected networks (VPN, Ethernet, Cellular, Wimax, Wifi)
** Unconnected networks (same order)

BUG=137941
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=150607

[stevenjb, 2012-08-07 21:57:19]

P1 for M22, ready for review when you have a chance.

[sadrul, 2012-08-08 14:59:20]

LGTM