Move admin0 server functions around

- move files to its right place
- add some boilerplate for test setup
- add tests

server/extension/expected/00_install_test.out

@@ -6,3 +6,18 @@ CREATE EXTENSION cartodb;
 CREATE EXTENSION cdb_geocoder;
 -- Install the extension
 CREATE EXTENSION cdb_geocoder_server;
+-- Mock the varnish invalidation function
+-- (used by cdb_geocoder tests)
+CREATE OR REPLACE FUNCTION public.cdb_invalidate_varnish(table_name text) RETURNS void AS $$
+BEGIN
+  RETURN;
+END
+$$
+LANGUAGE plpgsql;
+-- Set user quota
+SELECT cartodb.CDB_SetUserQuotaInBytes(0);
+ cdb_setuserquotainbytes 
+-------------------------
+                       0
+(1 row)
+

server/extension/expected/30_admin0_test.out

@@ -0,0 +1,24 @@
+-- Check that the public function is callable, even with no data
+-- It should return NULL
+SELECT cdb_geocoder_server.geocode_admin0_polygons(session_user, txid_current(), 'Spain');
+ geocode_admin0_polygons 
+-------------------------
+ 
+(1 row)
+
+-- Insert some dummy synonym
+INSERT INTO admin0_synonyms (name, adm0_a3) VALUES ('Spain', 'ESP');
+-- Insert some dummy geometry to return
+INSERT INTO ne_admin0_v3 (adm0_a3, the_geom) VALUES('ESP', ST_GeomFromText(
+  'POLYGON((-71.1031880899493 42.3152774590236,
+            -71.1031627617667 42.3152960829043,
+            -71.102923838298 42.3149156848307,
+            -71.1031880899493 42.3152774590236))',4326)
+);
+-- This should return the polygon inserted above
+SELECT cdb_geocoder_server.geocode_admin0_polygons(session_user, txid_current(), 'Spain');
+                                                                      geocode_admin0_polygons                                                                       
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------
+ 0103000020E61000000100000004000000D0EA37A29AC651C00FD603035B284540FEFCFB379AC651C0C0503E9F5B284540FFDDDD4D96C651C033AC3B284F284540D0EA37A29AC651C00FD603035B284540
+(1 row)
+