Margin loss
Margin loss


Former-commit-id: 2af542cc6b99cdf3e0e024d4e0ed13f6e2600053
Former-commit-id: 83994aa8f3444459cd177d14914e14b05be4f2f8
matt-gardner/deep_qa,matt-gardner/deep_qa,DeNeutoy/deep_qa,DeNeutoy/deep_qa,allenai/deep_qa,allenai/deep_qa