Notify when autobatching is used by Dynet
Notify when autobatching is used by Dynet

Former-commit-id: 4e88a02a36df8cb624ac9d65bf775330fc79c59c
shuheik/dynet,clab/dynet,danielhers/dynet,clab/dynet,danielhers/dynet,clab/dynet,xunzhang/dynet,shuheik/dynet,danielhers/dynet,clab/dynet,clab/cnn,chunyang-wen/dynet,clab/cnn,danielhers/dynet,clab/dynet,shuheik/dynet,xunzhang/dynet,xunzhang/dynet,xunzhang/dynet,danielhers/dynet,danielhers/dynet,chunyang-wen/dynet,shuheik/dynet,clab/cnn,chunyang-wen/dynet,shuheik/dynet,shuheik/dynet,clab/dynet,chunyang-wen/dynet,shuheik/dynet,danielhers/dynet,clab/dynet