Delay index creation w/ PostGIS PostgreSQL ogr2ogr driver

[sfrost@…]

When loading data into PostgreSQL it takes a great deal longer if an index is
already in place than it takes to load all the data and then generate an index.
 It would be nice to have an option to ogr2ogr to tell it to not create an index
on the table initially so that when doing batch loads the load will go much
faster.  The index/constraint could then be applied at the end of the load
either by the user (probably best, just have to command in the manpage next to
the option to disable it) or by a special call to ogr2ogr.

[warmerdam]

Stephen, 

I have reviewed the existing PostgreSQL/PostGIS driver, and I don't believe it
ever builds the spatial index automatically.  It seems you need to do that
manually after the fact, 

[hobu]

AFAIK, the PostGIS driver does not create an index upon layer creation, but there is a layer creation option proposed in #959 that might make it in if there is time.