Clean up logstash Jenkins console logs.

* modules/openstack_project/files/logstash/log-pusher.py: Change
@message to event_messsage. Using @message here appears to confuse
logstash and results in duplicate events.

* modules/openstack_project/templates/logstash/agent.conf.erb: Change
@message to event_messsage. Using @message here appears to confuse
logstash and results in duplicate events. Also drop the opening and
closing pre tags that end up in the html log files.

Change-Id: I3cf679dc644392cfb8ef9002cf149d8b449ad4f5
Reviewed-on: https://review.openstack.org/26518
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins
Handle mulitline console log lines.

* modules/openstack_project/templates/logstash/agent.conf.erb: Add
multiline filters to properly capture multiline log lines that do not
include their own timestamp.

Change-Id: I127e327cf6bdde580dcdfbe185f77fae3bd8d2c5
Reviewed-on: https://review.openstack.org/26530
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins
Remove redundant log fields.

* modules/openstack_project/templates/logstash/agent.conf.erb: Remove
logdate and logmessage fields when we are done with them. This reduces
the size of each log event.

Change-Id: I0b102d437397858d07cfc38498bc6b431199d3a4
Reviewed-on: https://review.openstack.org/26531
Reviewed-by: James E. Blair <corvus@inaugust.com>
Approved: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Tested-by: Jenkins