GEOT-4163 - Make dimension a first class information (like srid) in JDBC data stores

Hi,
this one has been sitting as a patch in Jira for a long while, believe it was not committed only because were were too close to a released.
Refreshed it a bit, and to make it work fully, had to improve the way we mimick postgis geometry columns creation, the CHECK are only used by postgis < 2.0, whilst postgis 2.0 and up uses built in type checks I believe (and had to specify the proper geometry type name for 3d geometries).

More info in Jira: https://jira.codehaus.org/browse/GEOT-4163