Implement CDB_QueryStatements as SQL language function

Do not relies on cartodb-postgresql extension which relies on
plpythonu language. That avoid installing it in travis-ci.

test/support/prepare_db.sh

@@ -78,8 +78,6 @@ if test x"$PREPARE_PGSQL" = xyes; then
     sed "s/:TESTPASS/${TESTPASS}/" |
     psql -v ON_ERROR_STOP=1 ${TEST_DB} || exit 1
 
-  psql -c "CREATE LANGUAGE plpythonu;" ${TEST_DB}
-  curl -L -s https://github.com/CartoDB/cartodb-postgresql/raw/cdb/scripts-available/CDB_QueryStatements.sql -o sql/CDB_QueryStatements.sql
   curl -L -s https://github.com/CartoDB/cartodb-postgresql/raw/cdb/scripts-available/CDB_QueryTables.sql -o sql/CDB_QueryTables.sql
   cat sql/CDB_QueryStatements.sql sql/CDB_QueryTables.sql sql/CDB_Overviews.sql |
     psql -v ON_ERROR_STOP=1 ${TEST_DB} || exit 1

test/support/sql/CDB_QueryStatements.sql

@@ -1,3 +1,6 @@
+-- DUMMY IMPLEMENTATION
+-- Ref: https://github.com/CartoDB/cartodb-postgresql/blob/master/scripts-available/CDB_QueryStatements.sql
+
 -- Return an array of statements found in the given query text
 --
 -- Regexp curtesy of Hubert Lubaczewski (depesz)
@@ -5,10 +8,9 @@
 --
 CREATE OR REPLACE FUNCTION CDB_QueryStatements(query text)
 RETURNS SETOF TEXT AS $$
-  import re
-  pat = re.compile( r'''((?:[^'"$;]+|"[^"]*"|'[^']*'|(\$[^$]*\$).*?\2)+)''', re.DOTALL )
-  for match in pat.findall(query):
-    cleaned = match[0].strip()
-    if ( cleaned ):
-      yield cleaned
-$$ language 'plpythonu' IMMUTABLE STRICT;
+  with matches as (
+    select regexp_matches($1, $regexp$((?:[^'"$;]+|"[^"]*"|'[^']*'|(\$[^$]*\$).*?\2)+)$regexp$, 'g') as m
+  )
+  select btrim(m[1]) from matches
+$$
+LANGUAGE SQL IMMUTABLE STRICT;