Logging features for Fuel and OpenStack

user-guide/config -- debug logging, configure syslog

op-guide/troubleshooting -- using logs

terminology/logging -- brief overview of logging facilities with
links to our docs and community docs for additional information

Change-Id: I06a5ed5f2e23be6c677177dff03cb8ceb0bb5215
Partial-Bugs: 1321200