Readme update

Found out that py2exe works on Python 3 as of about a month ago!  Switched the
standalone requirement to py2exe, as it provides a nicer, cleaner finished
product.
Better method for dealing with the wxPython warning

Tell the warnings module to ignore the warning, which has the added benefit of
preventing the message from showing up in the Standalone version as well.
changes needed for py2exe version:

* version for building the exe
* changes to translations to work properly