Support 'infinite' dhcp_lease_duration

Process a dhcp_lease_duration value of -1 as 'infinite'
when setting the dnsmasq dhcp-range values to support
cases where it is undesirable for instance dhcp leases
to expire.

DocImpact

Closes-Bug: #1315430
Change-Id: I1cc3cfebfec355014e6d5b5cbd656a1300c43c0b
Fix KeyError exception while updating dhcp port

This is caused by a missing network_id in the port body.
This patch adds it so that a warning message can be traced
correctly. Wording is slightly tweaked to ensure it applies
to the right context.

Closes-bug: #1324194

Change-Id: I4b67b5c3584aa33278eb0e9e879ca338ba0ca8b0
Revert "fix openvswitch requirement check"

This reverts commit be340d1bab015c47650687f97393c6c9015fb537.

The fix did not fix anything.
See comments at
https://review.openstack.org/#/c/95592/

Change-Id: I2926acf4b0a7020a7ad3237e6d03d5b78bfcb6c4
Merge "Support 'infinite' dhcp_lease_duration"
Merge "Revert "fix openvswitch requirement check""
FWaaS plugin doesn't need to handle firewall rule del ops

If firewall rule is attached to firewall policy, it would raise
FirewallRuleInUse excpetion in DB ops, else it is a pure DB delete ops.
So it is useless to handle delete_firewall_rule ops in fwaas plugin.
Closes-Bug: #1322076

Change-Id: I55a000d206f232c79b41230f526007f684db8f4f
Merge "FWaaS plugin doesn't need to handle firewall rule del ops"
Merge "Fix KeyError exception while updating dhcp port"