fixed database migration dependencies

Fixes pulling down of database-migration-1.0 jar and inclusion in the WAR.

How to reproduce:
 * Login to a clean slate machine (at least with a **clean slate home directory**)
 * Run `grails war`
 * Look inside the created WAR file and look for `liquibase` and `shiro` under `WEB-INF/lib` - it wouldn't be there
 * Apply the following branch and run `grails war`
 * Created WAR will have the required jars

**Those jars will be cached** - if you attempt to run again `grails war` on a machine with cached jars - things will work normally!!