Move Setting instantiation out of constructor

CroogoPlugin is used during installation, and as such might not have
the necessary models available.  Move it out of constructor so that
instantiating CroogoPlugin class does not fail.
Removing unneeded CroogoPlugin class from tests
Merge branch 'master' into 1.6
Trackable: Activate only when required fields exists
Trackable: check that session has already started
Change AclActionsControllerTest to use mocked components