The MediaWiki minimum version is 1.23.0.
Also, make sure you have the GMP and GD extensions for PHP. In Debian/Ubuntu install:
$ sudo apt-get install php5-gmp php5-gd
Add the following line in your LocalSettings.php
.
require_once( "$IP/extensions/BitId/BitId.php" );
In the shell run the update script:
$ cd $IP/maintenance
$ php update.php