Add filtration rule into stats collector for 7.0 FUEL release

[Alexander Kislitsky]

We should start to collect statistics of MOS 7.0 release from 24-Sep-2015 (date of public release is 30-Sep-2015).
Filtration rule should be added into external collector config on the following production servers:
- collector.mirantis.com
- collector.fuel-infra.org

After changing config restart uwsgi service and check records for release 7.0 are appeared in DB with status: installation_structures.is_filtered = FALSE

[Alexander Kislitsky (akislitsky)]

During adding rule is highly recommended to check stats from our test labs in DB.
7.0 release supports HTTP header master-node-uid for easy detecting origin of trash stats traffic.

Release is coming. Changing Importance to High.

[Fuel Devops McRobotson (fuel-devops-robot)]

Related fix proposed to branch: master
Change author: Alexander Charykov <email address hidden>
Review: https://review.fuel-infra.org/11879

[Fuel Devops McRobotson (fuel-devops-robot)]

Reviewed: https://review.fuel-infra.org/11879
Submitter: Alexander Charykov <email address hidden>
Branch: master

Commit: 66f9e6c2748848a1978e7d2877038dfc9e8f8aa0
Author: Alexander Charykov <email address hidden>
Date: Fri Sep 18 18:46:38 2015

Add master-node-uid to nginx log_format

This needed for extended filtering of statistics.

Related-Bug: #1494193
Change-Id: I946d0d4961ab0604603eee1b85220fa9aec6f92b