create a cli with python.
python will be installed by default on a lot of system.
* use getpass python native module
Fixes: https://github.com/lesspass/lesspass/issues/305
* use lesspass python code generator from Maurits van der Schee
Fixes: https://github.com/lesspass/lesspass/issues/328
tested with python2.7 and python3.6
breaking changes:
* -c is associated with --copy flag to copy the password
* -C is associated with the counter (previously -c)