#26 ogfs_expand and mkfs.ogfs disagree on rg layout

[Dominik Vogt]

The mkfs.ogfs and ogfs_expand tools use different
algorithms to deternime the number of resource groups
in a sub pool.

* mkfs.ogfs enforces at least 10 rgs is the pool is
small while ogfs_expand is happy with a single rg.
* mkfs.ogfs creates separate rgs in each sub pool, but
ogfs_expand just creates one set of rgs for all sub
pools that were added. Some new rgs may even cross the
sub pool boundary.