SINGA-390 Update installation.md
SINGA-390 Update installation.md

- update the installation command for installing SINGA with CUDA and cuDNN

apache/incubator-singa,kaiping/incubator-singa,apache/incubator-singa,kaiping/incubator-singa,apache/incubator-singa,kaiping/incubator-singa,ijingo/incubator-singa,nudles/incubator-singa,nudles/incubator-singa,apache/incubator-singa,ijingo/incubator-singa,nudles/incubator-singa,nudles/incubator-singa,nudles/incubator-singa,ijingo/incubator-singa,ijingo/incubator-singa,nusdbsystem/incubator-singa,kaiping/incubator-singa,nusdbsystem/incubator-singa,nusdbsystem/incubator-singa,nusdbsystem/incubator-singa,apache/incubator-singa,kaiping/incubator-singa,nusdbsystem/incubator-singa,ijingo/incubator-singa