Install pip3 on ubuntu16.04

1. Get get-pip.py on https://bootstrap.pypa.io/get-pip.py

2. Run sudo python3.5 get-pip.py --prefix=/usr/local/
    It will install pip packages in /usr/local folder

3. Then you can check packages are up-to-date by command:
    pip install --upgrade pip setuptools wheel

Reference:
https://packaging.python.org/tutorials/installing-packages/#requirements-for-installing-packages