D15714: add a string suffix to test data and use for unicode testing of taglibwriter

[Alexander Stippich]

astippich marked 5 inline comments as done.

REPOSITORY
  R286 KFileMetaData

REVISION DETAIL
  https://phabricator.kde.org/D15714

To: astippich, mgallien, bruns
Cc: smithjd, svuorela, kde-frameworks-devel, #baloo, ashaposhnikov, michaelh, 
astippich, spoorun, ngraham, bruns, abrahams