minion-sim: add DEFAULT_CRUSH_MAP_TEXT

Needed for doc generation (fills osd_map's crush_map_text)

Signed-off-by: Dan Mick <dan.mick@inktank.com>
Merge pull request #174 from ceph/wip-minion-sim-crush-text

minion-sim: add DEFAULT_CRUSH_MAP_TEXT

Reviewed-by: John Spray <john.spray@inktank.com>