allow user to add config during baremetal auto port-channel creation

[Carol Bouchard]

Provide the ability to allow the user to provide unique port-channel cli commands for configuring port-channels. To provide the commands, the user configures them in the ml2_conf_cisco.ini file as follows:
This is an optional configuration and they will be prepended with 'int port-channel x ;'. Do notice
this can be configured per switch.

[ml2_mech_cisco_nexus:your-unique-switch-ip]
<SNIP>
intfcfg.portchannel=no lacp suspend-individual;spanning-tree port type edge trunk

When there is no user port-channels commands configured, the following is applied when creating port-channels.

interface port-channelx
  switchport mode trunk
  switchport trunk allowed vlan none
  spanning-tree port type edge trunk
  no lacp suspend-individual
  vpc x

When user commands are provided, the following is configured by Nexus Driver followed by whatever user commands were configured in the ml2_conf_cisco.ini file for this port-channel on this switch:
interface port-channelx
  switchport mode trunk
  switchport trunk allowed vlan none
  vpc x

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/488159

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/488159
Committed: https://git.openstack.org/cgit/openstack/networking-cisco/commit/?id=21c5674a28ac38a16d679a2a3c45d373b7206c2e
Submitter: Jenkins
Branch: master

commit 21c5674a28ac38a16d679a2a3c45d373b7206c2e
Author: Carol Bouchard <email address hidden>
Date: Thu Jul 27 15:07:56 2017 -0400

    Allow user provided port-channel commands

    During automated port-channel creation, ML2 Nexus driver allows user
    to provide their own port-channel configured. This codeset provides
    an optional config option 'intfcfg.portchannel' in the
    ml2_conf_cisco.ini file which allows user to pass port-channel config
    commands for each switch. These commands will be prepended with
    'int port-channel x ;'. The following is a sample of such a config.
    Each command must be separated by ';'.

    [ml2_mech_cisco_nexus:your-unique-switch-ip]
    <SNIP>
    intfcfg.portchannel=your-port-channel-cmd1;your-port-channel-cmd2

    When there is no user port-channels commands configured, the following
    is applied when creating port-channels.

    interface port-channelx
      switchport mode trunk
      switchport trunk allowed vlan none
      spanning-tree port type edge trunk
      no lacp suspend-individual
      vpc x

    When user commands are provided, the following is configured by the
    Nexus Driver followed by whatever user commands were configured in the
    ml2_conf_cisco.ini file for this port-channel on this switch:
    These user commands are sent by way of NXAPI cli_conf.

    interface port-channelx
      switchport mode trunk
      switchport trunk allowed vlan none
      vpc x

    Change-Id: I0c0c40990b51a3c7c124debab2e190190e7747b0
    Closes-bug: #1706965