Fix flaky test due to numerical gradient approximation error.
Fix flaky test due to numerical gradient approximation error.

Summary:
Use smaller step size for GradientChecks and pass seed to help reproducing the
test from logged inputs.

Reviewed By: Yangqing

Differential Revision: D5505698

fbshipit-source-id: fc308efe72d535695ba628944aee1913ba16b2f1

sf-wind/caffe2,Yangqing/caffe2,pietern/caffe2,xzturn/caffe2,xzturn/caffe2,davinwang/caffe2,pietern/caffe2,pietern/caffe2,xzturn/caffe2,xzturn/caffe2,Yangqing/caffe2,pietern/caffe2,Yangqing/caffe2,Yangqing/caffe2,davinwang/caffe2,sf-wind/caffe2,pietern/caffe2,sf-wind/caffe2,sf-wind/caffe2,sf-wind/caffe2,davinwang/caffe2,davinwang/caffe2,caffe2/caffe2,davinwang/caffe2,xzturn/caffe2,Yangqing/caffe2