fixes #122
Adde support for passing empty list by using input-form attribute.

Sometiems it can be usefull to pass an empty list (e.g. because it is
filtered). But because of elivis operator it took full list of domain.
add default rendering for Blobs
Add Grails 2.3 test project.
Remove grailsRepo reference as no longer supported by Grails.
Fix test project for Grails 2.3 scaffolding.

The scaffolding templates changed between Grails 2.2 and 2.3, so the old
templates weren't working. The scaffolding's `list` action has also been
changed to `index`, so the test project needed updating for that too.
Added information about the performance difference between development and production environments
- fix