Release: Added internalization

        * .gitignore: added a few files generated by localizable mechanism
          to ignored list
        * Makefile.am: added 'po' directory to subdirs
        * configure.ac: added GETTEXT
        * po/LINGUAS: import polish language as a first translation
        * po/Makevars: makevars config file
        * po/POTFILES.in: list of files with translable text
        * po/gstreamer-studio.pot: pot file
        * po/pl.po: polish translation file
        * src/clients/studio/Makefile.am: libinit library linked
          passed localedir to an application
        * src/clients/studio/factoryinfowindow.cpp:
        * src/clients/studio/gstreamer-studio.cpp:
        * src/clients/studio/plugininfowindow.cpp:
        * /=src/core/plugininfo.cpp: made text translatable
        * src/config.h.in: input configuration file
        * src/core/Makefile.am: some flags allowing create translatable
          strings
        * src/gettext.h: gettext header