Update setup_centos_5.py

Invalid package name of libssh2-devel
Update setup_centos_5.py

Solve "error: Failed dependencies: /usr/local/bin/python is needed by NodeAgent-1.2.1-1.x86_64".

Python may be installed at /usr/bin/python .
Path modification
Merge pull request #14 from ironfeet/master

Update setup_centos_5.py Thank you for your commit