increase concurrency default
increase concurrency default

Summary: Huge improvement in my tests, and it does not really hurt either.

Reviewed By: wesolwsk

Differential Revision: D5374925

fbshipit-source-id: c96a4ed2ca653120a82233c0037cbfded8a2d2a1

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