Use SSD disk for journal device

use rotational info read by ohai plugin

default value for new partition start

--journal-dev does not use device as argument; real journal device comes to the end of command

bigger default value of journal size

spread the journals roughly equally among available SSD devices

make it configurable if SSD should be used for journal

added new osd settings to schema

use ceph-disk to create partition on given device

for first avaialble, do not add extra journal disk
allow user to specify list of journal partitions
Merge pull request #52 from jsuchome/ssd_for_journal

Use SSD disk for journal device