Integration of OpenStack Ceilometer metering service

Implementation will contain two stages.

Stage 1. Summary:
* Support HA and non-HA ceilometer
* MySQL (OpenStack DB) as database backend for ceilometer
* OSTF ceilometer testing
Limitations:
* no MongoDB support(default db backend)

Stage 2. Summary:
* Support MongoDB as backend
* Deploying MongoDB for production use cases

Acceptance criteria for testing:

By default ceilometer is disabled. To enable you should set "ceilometer" checkbox to true.

General:
1) On controller: "source openrc && ceilometer meter-list" . Command should not fail.
2) On compute: "ps aux|grep ceilometer". There should be a process "ceilometer-agent-compute".
3) If syslog used(default), on every node file "/etc/rsyslog.d/51-ceilometer.conf" should be presented.

For simple mode:
1) On controller: "ps aux|grep ceilometer". There should be a 3 processes: ceilometer-api, ceilometer-collector, ceilometer-agent-central.

For HA mode:
1) On every controller: "ps aux|grep ceilometer". There should be at least 2 processes: ceilometer-api, ceilometer-collector.
2) On every controller: "crm status|grep p_openstack-ceilometer-central". Find node where resource is started, ssh on this node and check process with "ps aux|grep ceilometer-agent-central"