Add --maintenance-interval to gnt-cluster modify
Add --maintenance-interval to gnt-cluster modify

...thus providing a convenient way to control at which
interval the maintenance daemon does its repairs.

Signed-off-by: Klaus Aehlig <4ce51de36d9068cd7db2eec1151e0f3f95419008@google.com>
Reviewed-by: Petr Pudlak <9d19625f8ee825a2c398462ed335cbcf98f79c32@google.com>

bitemyapp/ganeti,mbakke/ganeti,bitemyapp/ganeti,andir/ganeti,ganeti/ganeti,leshchevds/ganeti,leshchevds/ganeti,mbakke/ganeti,leshchevds/ganeti,andir/ganeti,ganeti/ganeti,ganeti/ganeti,onponomarev/ganeti,mbakke/ganeti,grnet/snf-ganeti,onponomarev/ganeti,grnet/snf-ganeti,andir/ganeti