Separate OSD scenarios to multiple files

Currently everything lives in main.yml, the file has become difficult to
read at some point and can be a real mess since we keep adding new
scenarios.
I think we should separate the scenarios into dedicated files and just
do includes in the main.yml file.

Closes: #16

Signed-off-by: Sébastien Han <sebastien.han@enovance.com>
Merge pull request #26 from leseb/wip-separate-osd-scenarios

Wip separate osd scenarios