vcsim: preserve order in QueryIpPools (#914)
vcsim: preserve order in QueryIpPools (#914)

IpPoolManager.pools is a map, so order is not guaranteed.  The test would sometimes fail with:

    ip_pool_manager_test.go:276: expect query result equal to ...
vmware/govmomi,bruceadowns/govmomi,dougm/govmomi,bruceadowns/govmomi,vmware/govmomi,dougm/govmomi,bruceadowns/govmomi,dougm/govmomi,vmware/govmomi