[stylable] Use PangoFontDescription to set the style on labels
[stylable] Use PangoFontDescription to set the style on labels

Rather than manipulating the attributes on the text instead use a temporary
PangoFontDescription to set the family, size and weight. This allows the
application to use markup or set its own attributes.

Fixes: http://bugzilla.moblin.org/show_bug.cgi?id=9287

jonnylamb/mx,pwithnall/mx,jonnylamb/mx,clutter-project/mx,pwithnall/mx,clutter-project/mx,clutter-project/mx,jonnylamb/mx,pwithnall/mx,pwithnall/mx,clutter-project/mx,jonnylamb/mx