Only allocate an IP address on storage network for OSD nodes

The OSD nodes are the only ones requiring access to it.

http://ceph.com/docs/master/rados/configuration/network-config-ref/
Explicitly pass cluster name to "ceph-disk prepare"

Currently, it just works because we use the default cluster name, but if
it changes, then this will stop working.
Pass --zap-disk, not --zap to ceph-disk prepare

The real option is --zap-disk.
Fix crash on deactivating the ceph proposal

F, [2014-07-18T10:02:35.431448 #27874] FATAL -- : apply_role: Exception undefined method `+' for nil:NilClass /opt/dell/crowbar_framework/app/models/node_object.rb:87:in `find_node_by_name'
/opt/dell/crowbar_framework/app/models/ceph_service.rb:109:in `apply_role_pre_chef_call'
/opt/dell/crowbar_framework/app/models/service_object.rb:1212:in `apply_role'
/opt/dell/crowbar_framework/app/models/service_object.rb:569:in `destroy_active'
/opt/dell/crowbar_framework/app/controllers/barclamp_controller.rb:415:in `proposal_update'
Merge pull request #70 from vuntz/fix-deactivate

Fix crash on deactivating the ceph proposal
Merge pull request #68 from vuntz/ceph-disk-prepare

Make call to ceph-disk prepare more "correct"
Merge pull request #67 from vuntz/only-osd-on-storage

Only allocate an IP address on storage network for OSD nodes
Put any custom setting in the right section

We were putting global custom settings in [osd] and re-creating a
[osd]/[mon] section if there were custom settings.
Move "osd pool default" settings to global section in ceph.conf

That's where they belong.
Set reasonable values for some settings

- default pool size: number of OSD nodes, or 3 if more OSDs than that
- default pg and pgp: use algorithm mentioned at
  http://ceph.com/docs/master/rados/configuration/pool-pg-config-ref/
- crush chooseleaf type: use value as mentioned at
  http://ceph.com/docs/master/rados/configuration/ceph-conf/#example-ceph-conf

Fix https://bugzilla.novell.com/show_bug.cgi?id=887696
Merge pull request #69 from vuntz/fix-ceph.conf

Set reasonable values for some settings