Wheel support in pip needs current setuptools

When virtualenvs are used without distribute and an old setuptools
python package is installed in the system, upgrading pip in the
virtualenv won't ensure setuptools > 0.8 is installed which is required
by the pip wheel command. This patch upgrades setuptools if distribute
isn't used.

Signed-off-by: Franz Pletz <fpletz@fnordicwalking.de>
Merge pull request #52 from Mayflower/fix/pip-wheel-needs-current-setuptools

Wheel support in pip needs current setuptools
Version 1.6.2
Add path to requirements exec
remove duplicate pip_install exec for latest case
Merge pull request #54 from saz/patch-1

Add path to requirements exec
Merge pull request #55 from saz/patch-2

remove duplicate pip_install exec for latest case