Nova provides show and console output functionalities for a server.
Currently, there isn't a benchmark provided by rally that does the above.
This commit adds plugins that call nova client's get and get console output
methods for a given server, allowing to use those for benchmarking.
This patch also includes functional and unit tests for newly added plugins.
Co-Authored-By: Michal Stolarczyk <zerodivisible@gmail.com>
Change-Id: Ica8642ca8463b1bcba936e3c1d392b4588a56dc2