LibertyAttachable upgraded

I have done a bit of plumbing in LibertyAttachable->save to facilitate multiple uploads per page. LiberyAttachable->verify & save now expect any uploaded file to be shoved in $pParamHash{upload}. This allows the child class to decide what gets stored more easily, as is the case with TikiUser.

TikiUser now extends LibertyAttachable and can be though of as a full Content object.