message: Fixes a memory leak in sidre::DataStore
  The attributes in the AttributeCollection were not being deleted.
diff: @@ -127,6 +127,7 @@ DataStore::~DataStore()
  // clean up Groups and Views before we destroy Buffers
  delete m_RootGroup;
  destroyAllBuffers();
  + destroyAllAttributes();
  delete m_attribute_coll;
  if ( m_need_to_finalize_slic )
  