make upgrades easier
make upgrades easier


Former-commit-id: 7fca795a2abf5f01e0381ea59eec42aee951bd72
xunzhang/dynet,clab/dynet,danielhers/dynet,xunzhang/dynet,shuheik/dynet,chunyang-wen/dynet,clab/dynet,shuheik/dynet,clab/dynet,danielhers/dynet,clab/dynet,clab/cnn,clab/dynet,chunyang-wen/dynet,chunyang-wen/dynet,danielhers/dynet,danielhers/dynet,chunyang-wen/dynet,clab/cnn,shuheik/dynet,danielhers/dynet,danielhers/dynet,shuheik/dynet,xunzhang/dynet,clab/cnn,shuheik/dynet,xunzhang/dynet,shuheik/dynet,clab/dynet,danielhers/dynet,clab/dynet,shuheik/dynet