Prefix "ORDER BY id" with table name.

[JivanAmara]

The order-by addition to gpkg provider generates SQL that can fail when joined tables both have an "id" field.

2018/03/06 14:59:07 handlers.go:216: Getting page 0 (size 10) for 'land_polygons'
2018-03-06 14:59:45 [ERROR] gpkg.go:138: err during query: SELECT `id` AS fid, `geom` AS geom FROM boundary l JOIN rtree_boundary_geom si ON l.id = si.id WHERE geom IS NOT NULL AND minx <= 179.99999997494382 AND maxx >= -179.99999997494382 AND miny <= 85.05112877764508 AND maxy >= -85.05112877764508 ORDER BY id - ambiguous column name: id
getFeatureIds len: 33289