adding Versions model
adding Versions::add() into BaseModel::save()
adding generic _call helper method to ScaffoldController
adding VersionsController incl. custom 'restore' action
update Versions model with full functionality, incl. 'restore'
activate Versions in BaseModel
use custom index-view for Versions
adding docblocks to Versions model
corrected schema of Versions
Merge branch 'refs/heads/master' into feature/Versions
Merge branch 'refs/heads/feature/Versions'
add Contents::get()