Upgrade six to 1.7.3
Merge pull request #2006 from dstufft/upgrade-six

Upgrade six to 1.7.3
Fix --no-cache-dir
Merge pull request #2010 from dstufft/fix-no-cache

Fix --no-cache-dir
Convert pip.compat into a package
Backport dictConfig (Taken from Django) for Python 2.6
Switch to using the stdlib logger instead of pip.log
Reimplement Logging Indentation
Allow a command to override what stream console logging goes to
Refactor to remove a now useless setup_logging hook
Move the pip.util module into a pip.utils package
Use the warnings system to handle deprecations
Remove the stuff in pip.log that we're no longer using
Move pip.log to pip.utils.logging
Use a custom StreamHandler subclass to colorize the log lines
Use a rotating appending log file which is always on for logging
Consolidate the logging file options into a single option
Implement and deprecate --log-explicit-levels
Vendor progress 1.2 to handle the progress bars in pip
Use the progress library to display download progress bars