[client] clean up status message creation.
[client] clean up status message creation.

closes #237.

ChristianNavolskyi/YCSB,manolama/YCSB,leschekhomann/YCSB,leschekhomann/YCSB,ChristianNavolskyi/YCSB,madhurihn/YCSB_ToyDB,leschekhomann/YCSB,brianfrankcooper/YCSB,jaemyoun/YCSB,manolama/YCSB,leschekhomann/YCSB,cricket007/YCSB,cricket007/YCSB,cricket007/YCSB,brianfrankcooper/YCSB,manolama/YCSB,ChristianNavolskyi/YCSB,jaemyoun/YCSB,madhurihn/YCSB_ToyDB,zyguan/ycsb,cricket007/YCSB,madhurihn/YCSB_ToyDB,manolama/YCSB,zyguan/ycsb,madhurihn/YCSB_ToyDB,jaemyoun/YCSB,jaemyoun/YCSB,brianfrankcooper/YCSB,zyguan/ycsb,zyguan/ycsb,ChristianNavolskyi/YCSB,brianfrankcooper/YCSB