added python

python added for personal interest
must be installed manually (not added to ant)
get pip and virtualenv for python

- pip (python package manager)
- virtualenv (python environment manager)
- added python/scripts to path for pip.exe and virtualenv.exe
added portable python

- added portable python download
- install instructions (not fully automated)
- removed unused lib/pip and lib/virtualenv folders
add watir-webdriver-performance gem

for getting browser performance metrics