Remove description method from PlaceholderInExtend

The `description` method is being deprecated.

Change-Id: I755e28a599f1cccdd38dafec1bf549e3f6b7e664
Reviewed-on: http://gerrit.causes.com/36723
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>