Renaming public schema breaks cstore

If we rename public schema then hardcoded function calls won't work, so cstore tables can't be dropped. I think this is not the intended behaviour either. See #125 for reference.

```
dev=# drop foreign table public.gen_releases;
ERROR: function public.cstore_clean_table_resources(oid) does not exist
LINE 1: SELECT public.cstore_clean_table_resources(v_obj.objid)
^
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
QUERY: SELECT public.cstore_clean_table_resources(v_obj.objid)
CONTEXT: PL/pgSQL function public_20190402_18.cstore_drop_trigger() line 10 at PERFORM
```

I tried to create a new cstore_server with different name but that didn't create the functions in public. Looks like I'd have to create these functions in public or move them back to public manually for all the functions.