[mongodb] Update the MongoDB driver version to 3.0.3.
[mongodb] Update the MongoDB driver version to 3.0.3.

Fixes #344.

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