Clarification of pip install -U help
Merge pull request #2098 from pfmoore/docfix

Clarification of pip install -U help
Fix to tox.ini so that pip.exe doesn't try to overwrite itself on Windows
Python 2.6 doesn't support python -m for packages
Merge pull request #2099 from pfmoore/toxfix

Fix to tox.ini so that pip.exe doesn't try to overwrite itself on Window...