Allow to specify a tablespace for a database

* Tablespaces have to be created before the databases
* Add pillar examples
* Add tests

pillar.example

@@ -47,6 +47,9 @@ postgres:
     - ['local', 'db1', 'localUser']
     - ['host', 'db2', 'remoteUser', '123.123.0.0/24']
 
+  tablespaces:
+    my_space: /srv/my_tablespace
+
   databases:
     db1:
       owner: 'localUser'
@@ -68,9 +71,10 @@ postgres:
       template: 'template0'
       lc_ctype: 'C.UTF-8'
       lc_collate: 'C.UTF-8'
+      tablespace: 'my_space'
       # optional extensions to enable on database
-      extensions:
-        postgis:
+      # extensions:
+      #   postgis:
   # backup extension defaults to .bak if postgresconf_backup is True.
   # Set to False to stop creation of backup on postgresql.conf changes.
   postgresconf_backup: True