* feat(fallback): add fallback JS & CSS

Issue [#806]

* feat(fallback): fix check option

Issue [#806]

* fix(package): create debian package with fallback files

issue #806

* fix(fallback): read parameter

issue [#806]

* ignore fallback fails on source

issue #806

* test(download): do not download iso and checks

issue #838

* test(KVM storage): check default storage on prepare

issue #843

* fix(KVM storage): use default storage for bases

issue #843

* refactor(backend): allow pass storage name to fetch path

issue #843