kv_flat_btree_async.cc: fix resource leak

Call AioCompletion::release() if the completion is no longer
needed to free the resources.

CID 727983 : Resource leak (RESOURCE_LEAK)
  leaked_storage: Variable "aioc" going out of scope leaks the
  storage it points to.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
kv_flat_btree_async.cc: fix AioCompletion resource leak

Call AioCompletion::release() if the completion is no longer
needed to free the resources.

CID 727981 (#3 of 3): Resource leak (RESOURCE_LEAK)
  leaked_storage: Variable "top_aioc" going out of scope leaks the
  storage it points to.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
Merge pull request #320 from dalgaaf/wip-da-CID-727983

kv_flat_btree_async.cc: fix resource leak
Merge pull request #321 from dalgaaf/wip-da-CID-727981

kv_flat_btree_async.cc: fix AioCompletion resource leak
osdmaptool: fix cli tests

Now that the default pool flags have changed.

Signed-off-by: Sage Weil <sage@inktank.com>
PendingReleaseNotes: notes about enabling HASHPSPOOL

Signed-off-by: Sage Weil <sage@inktank.com>