Delete subnet fails if assoc port has IPs from another subnet

This change fixes the following failure scenario:
- Create a network
- Create two subnets on the network
- Create a port on the network using one of the subnets
- Delete the other subnet
= = = > FAILURE: Subnet delete fails because supposedly there
is/are port(s) still associated with that subnet.

The problem addressed is that delete_subnet() in
neutron/db/db_base_plugin.py is checking for port(s) still being
associated with the subnet's network, not the subnet itself.

Change-Id: I7adbe18cce412135b2e42dcb7c592e60c1ec5f8f
Closes-Bug: #1281694
Add missing parameters for port creation

Recent API changes in N1KV controller require parameters such as
subnet id and IP address to handle port creation successfully.
Without these mandatory paramters, the REST call fails.
This patch addresses that by passing in the missing parameters
in the REST body.

Change-Id: I4cec6868051f492b9d1245ab201ff6c1a0837848
Closes-Bug: #1290561
Merge "Add missing parameters for port creation"
Merge "Delete subnet fails if assoc port has IPs from another subnet"