Changes:

No longer unconditionally adds a function to python-mode-hook.
Split the hook functions into a key binding one and a menu one.
Added to the Tools customization group.
pylint-options is now a list of strings.  This makes it easier to add and remove individual options.
Turn off reports by default.
Allow for a nonstandard pylint executable name with pylint-command.
Allow for unconditionally saving files before running (default is ask).
Prettier colors in the output buffer.
Make it work well with tramp.
Make it compatible with package.el.