Update INSTALL.md
Update INSTALL.md

Former-commit-id: e25b3241a0d07d6050f1907838a5396f67b6de96
shuheik/dynet,danielhers/dynet,clab/dynet,xunzhang/dynet,danielhers/dynet,xunzhang/dynet,clab/dynet,clab/dynet,clab/dynet,shuheik/dynet,xunzhang/dynet,clab/dynet,clab/dynet,clab/dynet,chunyang-wen/dynet,clab/cnn,shuheik/dynet,chunyang-wen/dynet,danielhers/dynet,chunyang-wen/dynet,xunzhang/dynet,shuheik/dynet,danielhers/dynet,shuheik/dynet,chunyang-wen/dynet,shuheik/dynet,danielhers/dynet,danielhers/dynet,shuheik/dynet,clab/cnn,danielhers/dynet,clab/cnn