* Fixing encoding when tracking 404 and later other errors: by default urllib.quote does not encode the / but for our purposes we want to encode it so that the URL show up nicely in the reports
 * only tracking /From= if the referrer was actually set

git-svn-id: http://dev.piwik.org/svn/trunk@6100 59fd770c-687e-43c8-a1e3-f5a4ff64c105