External Build Log storage for Jenkins. Prototype #1

We would like to have a prototype of Build External Logging system.

Concept:

• External Storage: Elasticsearch-Logstash-Kibana stack
• Jenkins agents report their log events directly to system without passing master
• Do not store logs on a system disk
• Users are able to see build logs from Jenkins web UI
• Nice2Have: visualization does not require much resources from Jenkins (e.g. client-side implementation with a simple routing of requests for security purposes)