Fix version passing and updates to easy_install requires

This fixes an issue with passing glance_client via superglance config(ie. GLANCECLIENT_VERSION = 2) and updates easy_install to install dependencies.  Works as long as python-dev and libffi-dev packages are installed. So, Ubuntu install process would be:

`
apt-get install python-dev
apt-get install libffi-dev
python setup.py install
`