updated readme

ias root:

yum install libXScrnSaver

as user:

python -m pip install --upgrade pip  setuptools wheel

python -m  pip install Cheetah3

python -m  pip install xlrd==2.0.1

python -m  pip install openpyxl

python -m pip install pysimplegui

Install pyGen:

git clone git@git.ia2.inaf.it:gino.tosti/pygen.git

python setup.py bdist_wheel

python -m pip install dist/GenDevice-0.1-py3-none-any.whl