Update lib/active_record/connection_adapters/postgis_adapter/spatial_table_definition.rb

SpatialTableDefinition should subclass from ActiveRecord::ConnectionAdapters::PostgreSQLAdapter::TableDefinition instead of ActiveRecord::ConnectionAdapters::TableDefinition.  This way it will not lose added instance methods such as #tsvector for column creation, and schema.rb files will work properly.
only inherit from ConnectionAdapters::PostgreSQLAdapter::TableDefinition if possible
Merge pull request #44 from joenoon/patch-1

Update lib/active_record/connection_adapters/postgis_adapter/spatial_tab...