CLOUDSTACK-1668: Fix IP conflict in VPC tier

Currently, allPossibleIps return the Ip lists which include the gateway,
so we need to remove gateway ip from this list.

Now, for non-VPC network it works, because NetUtils.getAllIpsFromCidr
return the Ip lists which do not include the first IP of the network
(like 192.168.0.1).
We need too add the first IP into the returned Ip list, because it can
be used for VM if it is not the gateway IP (for example, VPC networks).

The corresponding patch for 4.0.1 has been posted on
https://reviews.apache.org/r/9923/

Signed-off-by: Chip Childers <chip.childers@gmail.com>
CLOUDSTACK-1511 and CLOUDSTACK-1446