App: Upgrade to Grails 2.2.3.

Closes #139.
App: Upgrade to Grails 2.2.4.

After numerous problems with Grails 2.2.3 his update jumps us forward
again to 2.2.4.

All tests and application executions now pass.
Merge pull request #139 from ausaccessfed/feature/#139-Grails-2.2.3

Upgrade to Grails 2.2.3