WMSTileFuser improvements

Added the possibility to access directly a file from the FileResource class.
Added ImageIO-Ext dependecies for optimizing the Png encoding.
Added new classes for handling the image writing/reading on the WMSTileFuser class by removing the ImageIO.read() and ImageIO.write() methods.
Modified WMSTileFuser class with the above described classes.
Modified WMSService class with 2 new parameters to set on the WMSTileFuser class.
Set to TRUE the WMSService parameter "fullWMS"