Sort order SQL injection in Administrate

In Administrate (rubygem) before version 0.13.0, when sorting by attributes on a dashboard, the direction parameter was not validated before being interpolated into the SQL query. This could present a SQL injection if the attacker were able to modify the `direction` parameter and bypass ActiveRecord SQL protections. Whilst this does have a high-impact, to exploit this you need access to the Administrate dashboards, which we would expect to be behind authentication. This is patched in wersion 0.13.0.