python little things

1) both python2 and python3 installed on windows
use python3:py -3 -m pip install robotframework-sshlibrary
use python2:py -2 -m pip install robotframework-sshlibrary

2) set windows pip configure
create a file nemed "pip.ini" in the directory(C:\Users\test\pip)
set config information in pip.ini

3) install python lib with requirements.cfg
pip install -r requirements.