DAOS-VOL

Merge pull request #161 in HDF5VOL/daos-vol from ~JHENDERSON/daos-vol:metadata_tuning to master

* commit '5de9878322ceac4ed97eed55cf5c4157f3f10cc5':
  Check creation property list lengths against default plist buffer sizes
  Check for default creation property lists on object opens
  Optimize memory allocations in H5_daos_link_read
  Ensure that H5_daos_link_write's update task is completed on failure
  Optimize memory allocations in H5_daos_link_write
  Cache default values for several HDF5 properties
  Support flags parameter for DAOS object update/fetch tasks
  Make sure dataset fill value buffer gets freed
  Move object copying in metadata benchmark into own test set
  Cache encoded default property list buffers
  Use H5_daos_attribute_get_akeys for attribute's raw data akey
  Avoid H5Pcopy where possible