actually test things in the topology test
one more check for id
do not limit geojson precsision

quick hand check proved that the topology couchdb is the
same size (117kb) for the test case whether I use the default
16 decimal precision in the st_asgeojson, or whether I limit
it to 7.  So go with the higher precision.

Still a strange issue that the 4326 reprojection has more arcs
than the default, custom projection one.

modified:   lib/grid_topology.js
modified:   test/test_grid_topology.js