Exclude tables with table_type of VIEW

This excludes views registered by PostGIS 2.x like geography_columns, geometry_columns, raster_columns and raster_overviews.
The table_name != 'geometry_columns' is kept for PostGIS 1.5 compatibility. The type changed to VIEW in PostGIS 2.0.
Add functional test to ensure views are excluded by listTables()
Merge pull request #725 from jsor/fix-list-table-sql-for-postgresql-with-postgis

Exclude tables with table_type of VIEW