Replace quoted_printable_encode implementation by a more recent comment, since an user reported it as buggy
Replace quoted_printable_encode implementation by a more recent comment, since an user reported it as buggy

Freeaqingme/Z-Push-contrib,fmbiete/Z-Push-contrib,Zentyal/Z-Push-contrib,mta59066/Z-Push-contrib,RavenB/Z-Push-contrib,Takika/Z-Push-contrib