Add export sample functionality

Export your map in dxf, shp, tiff, and every formats supported by Gdal::ogr2ogr. 

That Sample show how to export from a postgis database to an esri shapefile using gdal ogr2ogr
You need to install gdal binaries (apt-get install gdal-bin) and adapt the ogr2ogr command.
Can be adapted to export/import almost everything (look at http://www.gdal.org/ogr/ogr_formats.html)

Regards
Nicolas Liaudat - nliaudat@pompiers-chatel.ch