Fixed Encoding Issues for Vietnamese Addresses

1. add.php: for the insert query I specify the entry for column address and owner name with _utf8
2. in admin/edit.php, admin/index.php I set the connection to UTF-8
3. when inserting Vietnamese chars correctly reading the entries in the admin (edit) view has wrong decoding in the browser, adding the `<meta charset="utf-8">` fixed that.

I did not test it with all other characters and languages whether they are well encoded. This need to be reviewed.