- Add Q_PLUGIN_METADATA for Qt 5, use Q_EXPORT_PLUGIN
  for Qt 4.
- Generate the Json files for Qt 5 from the pluginspec
  files by using a XSLT sheet.

Change-Id: I8653f182ae7d61615971c093df10b84fb06c2172
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>