Added Operation Guide.

This patch adds the latest Operation Guide in AsciiDoc format.

The sources have been converted from the existing DITA sources as of
Git commit a9372bf4ce from the master branch of the Midokura
Documentation repository: https://github.com/midokura/midonet-docs

Change-Id: I46e0e3e1d717086cdb59fb281a9eef1b435b91ee
Signed-off-by: Jan Hilberath <jan@midokura.com>