CLOUDSTACK-7855: NIC3 should set MTU and not NIC1 for storage network nic

The fix also persists the configuration in /etc/network/interfaces

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>
CLOUDSTACK-7854: Don't remove vm_template row for centos 5.5, mark as removed

Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>
(cherry picked from commit fda4b9ba2c2884960d5709952233a5551e900ebd)
Signed-off-by: Rohit Yadav <rohit.yadav@shapeblue.com>