Clean up after tests

For #64

test/CDB_QueryTablesTest.sql

@@ -31,6 +31,8 @@ create table sc.test (a int);
 insert into sc.test values (1);
 WITH inp AS ( select 'select * from sc.test'::text as q )
  SELECT q, CDB_QueryTables(q) from inp;
+DROP TABLE sc.test;
+DROP SCHEMA sc;
 
 WITH inp AS ( select 'SELECT
 * FROM geometry_columns'::text as q )

test/CDB_QueryTablesTest_expect

@@ -13,5 +13,7 @@ CREATE SCHEMA
 CREATE TABLE
 INSERT 0 1
 select * from sc.test|{sc.test}
+DROP TABLE sc.test;
+DROP SCHEMA sc;
 SELECT
 * FROM geometry_columns|{pg_catalog.pg_attribute,pg_catalog.pg_class,pg_catalog.pg_namespace,pg_catalog.pg_type}