LU-57 Allow OSTs to be created with no primary node

LU-57 Allow OSTs to be created with no primary node

Add a --servicenode parameter for mkfs.lustre to treat all service
nodes equally.

Bugzilla: 19064
Change-Id: I15fc50ec7b808fac03dab92b8c0702a0d054b559
Signed-off-by: Bobi Jam <bobijam@whamcloud.com>
Reviewed-on: http://review.whamcloud.com/378
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Mikhail Pershin <tappro@whamcloud.com>
Tested-by: Liang Zhen <liang@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>