issue #1896

Before we creashed but sometimes hash URLs change and we
must allow the admin a successfull download anyway

issue #1895 

refactor: update ISO URLs in background

This will speed up startup

* feat: edit disk configuration only
* feat: get and set disk cache
* feat: change memory from hardware form

closes #1682

feat: apply changes to clones

refactor(frontend): improved add/edit hw form

refactor(test): improved mock VMs network ip

feat: manage CPU topology