Update INSTALL.md
Update INSTALL.md

Former-commit-id: 69f7d1a12c997acb399eed9fa660e8a3e511433d
shuheik/dynet,danielhers/dynet,chunyang-wen/dynet,clab/dynet,shuheik/dynet,shuheik/dynet,chunyang-wen/dynet,clab/dynet,danielhers/dynet,danielhers/dynet,clab/cnn,shuheik/dynet,danielhers/dynet,clab/dynet,xunzhang/dynet,clab/dynet,xunzhang/dynet,clab/cnn,danielhers/dynet,clab/cnn,shuheik/dynet,clab/dynet,clab/dynet,danielhers/dynet,clab/dynet,chunyang-wen/dynet,xunzhang/dynet,xunzhang/dynet,shuheik/dynet,shuheik/dynet,danielhers/dynet,chunyang-wen/dynet