lma collector: configure by default the alerting mode if the infra-alerting role is deployed

[Swann Croiset]

Currently, the "alerting" mode option for LMA collector plugin is error prone: because the user must explicitly select the radio "Alerts sent to a local node running the LMA Infrastructure Alerting plugin" to send service status to Nagios.

In practice, user deploys the 2 plugins but misses to select this option which lead UNKNOWN status for all service in Nagios UI.

Proposed change:
The LMA collector uses by default the "infrastructure alerting" plugin to send statuses if it is deployed within the environnement.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/275833

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/275833
Committed: https://git.openstack.org/cgit/openstack/fuel-plugin-lma-collector/commit/?id=baeca5ef6f64e1f6ee70a81a83f1077119a9c76f
Submitter: Jenkins
Branch: master

commit baeca5ef6f64e1f6ee70a81a83f1077119a9c76f
Author: Swann Croiset <email address hidden>
Date: Wed Feb 3 18:19:35 2016 +0100

    Try to configure Nagios by default

    The LMA collector uses by default the "infrastructure alerting" plugin
    to send statuses if it is deployed within the environnement.
    Previously, the user had to select explicitly the good option but
    in practice the user forgot to select this option which leads to UNKNOWN
    status for all service in the Nagios UI

    Change-Id: Ia08f7e7f6763aeb3710ba26f88bfce6130a218bd
    Fixes-bug: #1541462