Few fixes for translations (and translated doc)

- set Your names/Your emails as properties for KAboutData, according
  the guidelines;
- remove the translated po and the translated docbook, which will be
  copied to the translation repository (docbooks are going to be
  converted to po files);
- add a proper Messages.sh;
- add the macro for the installation of translated artifacts, which
  will be injected using releaseme at release time;
- fix the DTD used for the English documentation.